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Sample records for semiconductor lasers based

  1. Ring resonator based narrow-linewidth semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Ksendzov, Alexander (Inventor)

    2005-01-01

    The present invention is a method and apparatus for using ring resonators to produce narrow linewidth hybrid semiconductor lasers. According to one embodiment of the present invention, the narrow linewidths are produced by combining the semiconductor gain chip with a narrow pass band external feedback element. The semi conductor laser is produced using a ring resonator which, combined with a Bragg grating, acts as the external feedback element. According to another embodiment of the present invention, the proposed integrated optics ring resonator is based on plasma enhanced chemical vapor deposition (PECVD) SiO.sub.2 /SiON/SiO.sub.2 waveguide technology.

  2. Laser apparatus for surgery and force therapy based on high-power semiconductor and fibre lasers

    SciTech Connect

    Minaev, V P

    2005-11-30

    High-power semiconductor lasers and diode-pumped lasers are considered whose development qualitatively improved the characteristics of laser apparatus for surgery and force therapy, extended the scope of their applications in clinical practice, and enhanced the efficiency of medical treatment based on the use of these lasers. The characteristics of domestic apparatus are presented and their properties related to the laser emission wavelength used in them are discussed. Examples of modern medical technologies based on these lasers are considered. (invited paper)

  3. A design of atmospheric laser communication system based on semiconductor laser

    NASA Astrophysics Data System (ADS)

    Rao, Jionghui; Yao, Wenming; Wen, Linqiang

    2016-01-01

    This paper uses semiconductor laser with 905nm wave length as light source to design a set of short-distance atmospheric laser communication system. This system consists of laser light source, launch modulation circuit, detector, receiving and amplifying circuit and so on. First, this paper analyzes the factors which lead to the decrease of luminous power of laser communication link under the applicable environment-specific sea level, then this paper elicits the relationship of luminous power of receiving optical systems and distance, slant angle and divergence angle which departures from the laser beam axis by using gaussian beam geometric attenuation mode. Based on the two reasons that PPM modulation theory limits the transmission rate of PPM modulation, that is, this paper makes an analysis on repetition frequency and pulse width of laser, makes theoretical calculation for typical parameters of semiconductor laser and gets the repetition frequency which is 10KHz, pulse width is50ns, the transmission rate is 71.66 Kb/s, at this time, modulation digit is 9; then this paper selects frame synchronization code of PPM modulation and provides implementation method for test; lastly, programs language based on Verilog, uses the FPGA development board to realize PPM modulation code and does simulation test and hardware test. This paper uses APD as the detector of receiving and amplifying circuit. Then this paper designs optical receiving circuit such as amplifying circuit, analog-digital conversion circuit based on the characteristics of receipt.

  4. Web-based interactive educational software introducing semiconductor laser dynamics: Sound of Lasers (SOL)

    NASA Astrophysics Data System (ADS)

    Consoli, Antonio; Sanchez, Jorge R.; Horche, Paloma R.; Esquivias, Ignacio

    2014-07-01

    presented. The proposed tool is addressed to the students of optical communication courses, encouraging self consolidation of the subjects learned in lectures. The semiconductor laser model is based on the well known rate equations for the carrier density, photon density and optical phase. The direct modulation of the laser is considered with input parameters which can be selected by the user. Different options for the waveform, amplitude and frequency of the injected current are available, together with the bias point. Simulation results are plotted for carrier density and output power versus time. Instantaneous frequency variations of the laser output are numerically shifted to the audible frequency range and sent to the computer loudspeakers. This results in an intuitive description of the "chirp" phenomenon due to amplitude-phase coupling, typical of directly modulated semiconductor lasers. In this way, the student can actually listen to the time resolved spectral content of the laser output. By changing the laser parameters and/or the modulation parameters, consequent variation of the laser output can be appreciated in intuitive manner. The proposed educational tool has been previously implemented by the same authors with locally executable software. In the present manuscript, we extend our previous work to a web based platform, offering improved distribution and allowing its use to the wide audience of the web.

  5. Semiconductor microcavity lasers

    SciTech Connect

    Gourley, P.L.; Wendt, J.R.; Vawter, G.A.; Warren, M.E.; Brennan, T.M.; Hammons, B.E.

    1994-02-01

    New kinds of semiconductor microcavity lasers are being created by modern semiconductor technologies like molecular beam epitaxy and electron beam lithography. These new microcavities exploit 3-dimensional architectures possible with epitaxial layering and surface patterning. The physical properties of these microcavities are intimately related to the geometry imposed on the semiconductor materials. Among these microcavities are surface-emitting structures which have many useful properties for commercial purposes. This paper reviews the basic physics of these microstructured lasers.

  6. Subpicosecond Carrier Dynamics in Semiconductor Lasers and Lasers Based on Intersubband Transition.

    NASA Astrophysics Data System (ADS)

    Sung, Chun-Yung

    intersubband relaxation in stepped quantum well structures for far-infrared lasers were also measured. We have obtained quite good agreement between theoretical and experimental values for the intersubband relaxation rates in undoped structures. It is shown that the modified intersubband relaxation rates in the stepped quantum well allow us to establish a population inversion between subbands in both the proposed optically pumped and electrically pumped FIR semiconductor laser structures. When the n=3 state is pumped, a population inversion between n3 and n2 (separated by 7 THz) is observed, which will be appropriate for an optically-pumped FIR laser. Low-temperature-grown GaAs (LT-GaAs) is very important for many high speed optoelectronic application. Previous experiments have indicated the role of both EL2-like arsenic anti-site defect centers or arsenic precipitates in producing an ultrafast lifetime. We have performed a multi-wavelength pump-probe experiment to probe the separate electron and hole capture times. Using high carrier density excitation to saturate the midgap traps, we have determined the carrier life time in the defect band. A better understanding of the dynamics of electrons and holes in LT-GaAs will lead to optimization of electronic and photoconductive devices based on these materials.

  7. Widely tunable lasers based on mode-hop-free semiconductor laser array

    NASA Astrophysics Data System (ADS)

    Kurobe, T.; Kimoto, T.; Muranushi, K.; Mukaihara, T.; Ariga, M.; Kagimoto, T.; Kagi, N.; Matsuo, N.; Kasukawa, A.

    2007-11-01

    Integration of mode-hop-free tunable laser array and a semiconductor optical amplifier is most reliable approach to realize widely tunable lasers. We have developed two types of tunable lasers, one is a thermally tunable DFB laser array for DWDM tunable transponders, which has shown high power and wide tunability covering Cband or L-band, housing in compact butterfly packages with robust wavelength locker. Another is a short-cavity DBR laser array for optical burst switching, whose lasing frequency can be monotonously tuned and locked on the ITU grid within 5 microseconds. Both lasers have demonstrated superior performances in system experiments.

  8. Investigation of laser radar systems based on mid-infrared semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Rybaltowski, Adam

    This dissertation deals with the possibility of utilizing mid-infrared semiconductor lasers in systems of optical remote sensing with range resolution, called laser radar or lidar. The main subject investigated in this dissertation is two-fold: firstly, an analysis of the signal-to-noise ratio (SNR) and related maximum sensing range calculations in this type of lidar based on available system components, and---secondly---improvements in the Random-Modulation Continuous-Wave (RM-CW) lidar technique to better utilize available mid-infrared semiconductor lasers. As far as the SNR analysis is concerned, an appropriate framework has been constructed to analyze post-demodulation noise in mid-infrared direct-detection RM-CW lidar. It is based on a generalization of the Wiener-Khintchine theorem; noise is assumed to be additive, stationary, and have an arbitrary power spectrum. This is in contrast to the SNR analysis in the literature on this subject, which is inadequate for mid-infrared RM-CW lidar as it only considers Poissonian fluctuations of the number of detected photons. In addition to regular SNR analysis, the framework derived in this dissertation allows treatment of singularities such as demodulation with an unbalanced sequence in 1/f noise. To calculate maximum lidar sensing range, the following detection limits have been considered: signal shot noise, background blackbody radiation shot noise based on the Background-Limited Photodetection (BLIP) detectivity limit, and minimum-size detector noise given by diffraction-limited focusing. The latter is found to be of greatest practical interest. Furthermore, a lidar figure of merit has been introduced, and all quantities related to lidar performance and its detection limits have been presented graphically. Since pseudo-random sequences discussed in the literature have been found highly non-optimal for most applications of RM-CW lidar, a framework for the construction of new pseudo-random sequences of desired

  9. Tunable semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

    2006-01-01

    Tunable semiconductor lasers are disclosed requiring minimized coupling regions. Multiple laser embodiments employ ring resonators or ring resonator pairs using only a single coupling region with the gain medium are detailed. Tuning can be performed by changing the phase of the coupling coefficient between the gain medium and a ring resonator of the laser. Another embodiment provides a tunable laser including two Mach-Zehnder interferometers in series and a reflector coupled to a gain medium.

  10. Semiconductor nanowire lasers

    NASA Astrophysics Data System (ADS)

    Eaton, Samuel W.; Fu, Anthony; Wong, Andrew B.; Ning, Cun-Zheng; Yang, Peidong

    2016-06-01

    The discovery and continued development of the laser has revolutionized both science and industry. The advent of miniaturized, semiconductor lasers has made this technology an integral part of everyday life. Exciting research continues with a new focus on nanowire lasers because of their great potential in the field of optoelectronics. In this Review, we explore the latest advancements in the development of nanowire lasers and offer our perspective on future improvements and trends. We discuss fundamental material considerations and the latest, most effective materials for nanowire lasers. A discussion of novel cavity designs and amplification methods is followed by some of the latest work on surface plasmon polariton nanowire lasers. Finally, exciting new reports of electrically pumped nanowire lasers with the potential for integrated optoelectronic applications are described.

  11. Semiconductor laser-based ranging instrument for earth gravity measurements

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Millar, Pamela S.; Sun, Xiaoli

    1995-01-01

    A laser ranging instrument is being developed to measure the spatial variations in the Earth's gravity field. It will range in space to a cube corner on a passive co-orbiting sub-satellite with a velocity accuracy of 20 to 50 microns/sec by using AlGaAs lasers intensity modulated at 2 GHz.

  12. Laser beam shaping optical system design methods and their application in edge-emitting semiconductor laser-based LIDAR systems

    NASA Astrophysics Data System (ADS)

    Serkan, Mert

    LIDAR (Light Detection And Ranging) systems are employed for numerous applications such as remote sensing, military applications, optical data storage, display technology, and material processing. Furthermore, they are superior to other active remote sensing tools such as RADAR systems, considering their higher accuracy and more precise resolution due to their much shorter wavelengths and narrower beamwidth. Several types of lasers can be utilized as the radiation source of several LIDAR systems. Semiconductor laser-based LIDAR systems have several advantages such as low cost, compactness, broad range of wavelengths, and high PRFs (Pulse Repetition Frequency). However, semiconductor lasers have different origins and angles of divergence in the two transverse directions, resulting in the inherent astigmatism and elliptical beam shape. Specifically, elliptical beam shape is not desirable for several laser-based applications including LIDAR systems specifically designed to operate in the far-field region. In this dissertation, two mirror-based and two lens-based beam shapers are designed to circularize, collimate, and expand an edge-emitting semiconductor laser beam to a desired beam diameter for possible application in LIDAR systems. Additionally, most laser beams including semiconductor laser beams have Gaussian irradiance distribution. For applications that require uniform illumination of an extended target area, Gaussian irradiance distribution is undesirable. Therefore, a specific beam shaper is designed to transform the irradiance distribution from Gaussian to uniform in addition to circularizing, collimating, and expanding the semiconductor laser beam. For the design of beam shapers, aperture sizes of the surfaces are preset for desired power transmission and allowed diffraction level, surface parameters of the optical components and the distances between these surfaces are determined. Design equations specific to these beam shaping optical systems are

  13. Diode-Laser Pumped Far-Infrared Local Oscillator Based on Semiconductor Quantum Wells

    NASA Technical Reports Server (NTRS)

    Kolokolov, K.; Li, J.; Ning, C. Z.; Larrabee, D. C.; Tang, J.; Khodaparast, G.; Kono, J.; Sasa, S.; Inoue, M.; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    The contents include: 1) Tetrahertz Field: A Technology Gap; 2) Existing THZ Sources and Shortcomings; 3) Applications of A THZ Laser; 4) Previous Optical Pumped LW Generations; 5) Optically Pumped Sb based Intersubband Generation Whys; 6) InGaAs/InP/AlAsSb QWs; 7) Raman Enhanced Optical Gain; 8) Pump Intensity Dependence of THZ Gain; 9) Pump-Probe Interaction Induced Raman Shift; 10) THZ Laser Gain in InGaAs/InP/AlAsSb QWs; 11) Diode-Laser Pumped Difference Frequency Generation (InGaAs/InP/AlAsSb QWs); 12) 6.1 Angstrom Semiconductor Quantum Wells; 13) InAs/GaSb/AlSb Nanostructures; 14) InAs/AlSb Double QWs: DFG Scheme; 15) Sb-Based Triple QWs: Laser Scheme; and 16) Exciton State Pumped THZ Generation. This paper is presented in viewgraph form.

  14. Fibre ring cavity semiconductor laser

    SciTech Connect

    Duraev, V P; Medvedev, S V

    2013-10-31

    This paper presents a study of semiconductor lasers having a polarisation maintaining fibre ring cavity. We examine the operating principle and report main characteristics of a semiconductor ring laser, in particular in single- and multiple-frequency regimes, and discuss its application areas. (lasers)

  15. Simple and compact tunable semiconductor lasers based on novel half-wave coupler

    NASA Astrophysics Data System (ADS)

    He, Jian-Jun; Xiong, Xiaohai; Meng, Jianjun; Wu, Lin; Zhang, Sen; Liao, Xiaolu; Zou, Li

    2015-02-01

    Widely tunable semiconductor lasers based on a novel half-wave coupler are presented. They have been implemented in the form of half-wave coupled V-cavity and ring-FP cavities. By using the novel half-wave coupler, single-mode lasing with high side-mode-suppression-ratio is achieved. Single-electrode controlled wide-band wavelength tuning with Vernier effect is demonstrated. The full-band tuning of 50 channels with 100GHz spacing is realized by further employing temperature induced gain spectrum shift. The laser is packaged into a small-form-factor 9-pin box TOSA, and the electronic driver has been developed for the wavelength tuning and direct modulation. The advantages of compactness, fabrication simplicity, easy wavelength control and direct modulation allow the tunable lasers to be used in low-cost access and datacenter networks, as well as in portable devices for spectroscopic analysis.

  16. Influences of semiconductor laser on fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Liang, Sheng; Zhang, Chun-Xi; Lin, Bo; Lin, Wen-Tai; Li, Qin; Zhong, Xiang; Li, Li-Jing

    2010-12-01

    This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.

  17. Semiconductor Laser Low Frequency Noise Characterization

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Logan, Ronald T.

    1996-01-01

    This work summarizes the efforts in identifying the fundamental noise limit in semiconductor optical sources (lasers) to determine the source of 1/F noise and it's associated behavior. In addition, the study also addresses the effects of this 1/F noise on RF phased arrays. The study showed that the 1/F noise in semiconductor lasers has an ultimate physical limit based upon similar factors to fundamental noise generated in other semiconductor and solid state devices. The study also showed that both additive and multiplicative noise can be a significant detriment to the performance of RF phased arrays especially in regard to very low sidelobe performance and ultimate beam steering accuracy. The final result is that a noise power related term must be included in a complete analysis of the noise spectrum of any semiconductor device including semiconductor lasers.

  18. GaN nanostructure-based light emitting diodes and semiconductor lasers.

    PubMed

    Viswanath, Annamraju Kasi

    2014-02-01

    GaN and related materials have received a lot of attention because of their applications in a number of semiconductor devices such as LEDs, laser diodes, field effect transistors, photodetectors etc. An introduction to optical phenomena in semiconductors, light emission in p-n junctions, evolution of LED technology, bandgaps of various semiconductors that are suitable for the development of LEDs are discussed first. The detailed discussion on photoluminescence of GaN nanostructures is made, since this is crucial to develop optical devices. Fabrication technology of many nanostructures of GaN such as nanowires, nanorods, nanodots, nanoparticles, nanofilms and their luminescence properties are given. Then the optical processes including ultrafast phenomena, radiative, non-radiative recombination, quantum efficiency, lifetimes of excitons in InGaN quantum well are described. The LED structures based on InGaN that give various important colors of red, blue, green, and their design considerations to optimize the output were highlighted. The recent efforts in GaN technology are updated. Finally the present challenges and future directions in this field are also pointed out.

  19. Semiconductor optical amplifier-based heterodyning detection for resolving optical terahertz beat-tone signals from passively mode-locked semiconductor lasers

    SciTech Connect

    Latkowski, Sylwester; Maldonado-Basilio, Ramon; Carney, Kevin; Parra-Cetina, Josue; Philippe, Severine; Landais, Pascal

    2010-08-23

    An all-optical heterodyne approach based on a room-temperature controlled semiconductor optical amplifier (SOA) for measuring the frequency and linewidth of the terahertz beat-tone signal from a passively mode-locked laser is proposed. Under the injection of two external cavity lasers, the SOA acts as a local oscillator at their detuning frequency and also as an optical frequency mixer whose inputs are the self-modulated spectrum of the device under test and the two laser beams. Frequency and linewidth of the intermediate frequency signal (and therefore, the beat-tone signal) are resolved by using a photodiode and an electrical spectrum analyzer.

  20. Towards the generation of random bits at terahertz rates based on a chaotic semiconductor laser

    NASA Astrophysics Data System (ADS)

    Kanter, Ido; Aviad, Yaara; Reidler, Igor; Cohen, Elad; Rosenbluh, Michael

    2010-06-01

    Random bit generators (RBGs) are important in many aspects of statistical physics and crucial in Monte-Carlo simulations, stochastic modeling and quantum cryptography. The quality of a RBG is measured by the unpredictability of the bit string it produces and the speed at which the truly random bits can be generated. Deterministic algorithms generate pseudo-random numbers at high data rates as they are only limited by electronic hardware speed, but their unpredictability is limited by the very nature of their deterministic origin. It is widely accepted that the core of any true RBG must be an intrinsically non-deterministic physical process, e.g. measuring thermal noise from a resistor. Owing to low signal levels, such systems are highly susceptible to bias, introduced by amplification, and to small nonrandom external perturbations resulting in a limited generation rate, typically less than 100M bit/s. We present a physical random bit generator, based on a chaotic semiconductor laser, having delayed optical feedback, which operates reliably at rates up to 300Gbit/s. The method uses a high derivative of the digitized chaotic laser intensity and generates the random sequence by retaining a number of the least significant bits of the high derivative value. The method is insensitive to laser operational parameters and eliminates the necessity for all external constraints such as incommensurate sampling rates and laser external cavity round trip time. The randomness of long bit strings is verified by standard statistical tests.

  1. Bidirectional chaos communication between two outer semiconductor lasers coupled mutually with a central semiconductor laser.

    PubMed

    Li, Ping; Wu, Jia-Gui; Wu, Zheng-Mao; Lin, Xiao-Dong; Deng, Dao; Liu, Yu-Ran; Xia, Guang-Qiong

    2011-11-21

    Based on a linear chain composed of a central semiconductor laser and two outer semiconductor lasers, chaos synchronization and bidirectional communication between two outer lasers have been investigated under the case that the central laser and the two outer lasers are coupled mutually, whereas there exists no coupling between the two outer lasers. The simulation results show that high-quality and stable isochronal synchronization between the two outer lasers can be achieved, while the cross-correlation coefficients between the two outer lasers and the central laser are very low under proper operation condition. Based on the high performance chaos synchronization between the two outer lasers, message bidirectional transmissions of bit rates up to 20 Gbit/s can be realized through adopting a novel decoding scheme which is different from that based on chaos pass filtering effect. Furthermore, the security of bidirectional communication is also analyzed.

  2. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers

    PubMed Central

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-01-01

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing. PMID:27991574

  3. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers.

    PubMed

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-12-19

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing.

  4. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers

    NASA Astrophysics Data System (ADS)

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-12-01

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing.

  5. Quantitative analysis of uranium in aqueous solutions using a semiconductor laser-based spectroscopic method.

    PubMed

    Cho, Hye-Ryun; Jung, Euo Chang; Cha, Wansik; Song, Kyuseok

    2013-05-07

    A simple analytical method based on the simultaneous measurement of the luminescence of hexavalent uranium ions (U(VI)) and the Raman scattering of water, was investigated for determining the concentration of U(VI) in aqueous solutions. Both spectra were measured using a cw semiconductor laser beam at a center wavelength of 405 nm. The empirical calibration curve for the quantitative analysis of U(VI) was obtained by measuring the ratio of the luminescence intensity of U(VI) at 519 nm to the Raman scattering intensity of water at 469 nm. The limit of detection (LOD) in the parts per billion range and a dynamic range from the LOD up to several hundred parts per million were achieved. The concentration of uranium in groundwater determined by this method is in good agreement with the results determined by kinetic phosphorescence analysis and inductively coupled plasma mass spectrometry.

  6. Synchronized 4 × 12 GHz hybrid harmonically mode-locked semiconductor laser based on AWG.

    PubMed

    Liu, S; Lu, D; Zhang, R; Zhao, L; Wang, W; Broeke, R; Ji, C

    2016-05-02

    We report a monolithically integrated synchronized four wavelength channel mode-locked semiconductor laser chip based on arrayed waveguide grating and fabricated in the InP material system. Device fabrication was completed in a multiproject wafer foundry run on the Joint European Platform for Photonic Integration of Components and Circuits. The integrated photonic chip demonstrated 5th harmonic electrical hybrid mode-locking operation with four 400 GHz spacing wavelength channels and synchronized to a 12.7 GHz RF clock, for nearly transform-limited optical pulse trains from a single output waveguide. A low timing jitter of 0.349 ps, and RF frequency locking range of ~50 MHz were also achieved.

  7. A semiconductor-based, frequency-stabilized mode-locked laser using a phase modulator and an intracavity etalon.

    PubMed

    Davila-Rodriguez, Josue; Ozdur, Ibrahim; Williams, Charles; Delfyett, Peter J

    2010-12-15

    We report a frequency-stabilized semiconductor-based mode-locked laser that uses a phase modulator and an intracavity Fabry-Perot etalon for both active mode-locking and optical frequency stabilization. A twofold multiplication of the repetition frequency of the laser is inherently obtained in the process. The residual timing jitter of the mode-locked pulse train is 13 fs (1 Hz to 100 MHz), measured after regenerative frequency division of the photodetected pulse train.

  8. Excitability in optically injected semiconductor lasers: Contrasting quantum- well- and quantum-dot-based devices

    NASA Astrophysics Data System (ADS)

    Kelleher, B.; Bonatto, C.; Huyet, G.; Hegarty, S. P.

    2011-02-01

    Excitability is a generic prediction for an optically injected semiconductor laser. However, the details of the phenomenon differ depending on the type of device in question. For quantum-well lasers very complicated multipulse trajectories can be found, while for quantum-dot lasers the situation is much simpler. Experimental observations show the marked differences in the pulse shapes while theoretical considerations reveal the underlying mechanism responsible for the contrast, identifying the increased stability of quantum-dot lasers to perturbations as the root.

  9. Excitability in optically injected semiconductor lasers: contrasting quantum-well- and quantum-dot-based devices.

    PubMed

    Kelleher, B; Bonatto, C; Huyet, G; Hegarty, S P

    2011-02-01

    Excitability is a generic prediction for an optically injected semiconductor laser. However, the details of the phenomenon differ depending on the type of device in question. For quantum-well lasers very complicated multipulse trajectories can be found, while for quantum-dot lasers the situation is much simpler. Experimental observations show the marked differences in the pulse shapes while theoretical considerations reveal the underlying mechanism responsible for the contrast, identifying the increased stability of quantum-dot lasers to perturbations as the root.

  10. Semiconductor Laser Tracking Frequency Distance Gauge

    NASA Technical Reports Server (NTRS)

    Phillips, James D.; Reasenberg, Robert D.

    2009-01-01

    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require a spaceworthy laser distance gauge of substantially improved performance. The Tracking Frequency Gauge (TFG) uses a single beam, locking a laser to the measurement interferometer. We have demonstrated this technique with pm (10(exp -12) m) performance. We report on the version we are now developing based on space-qualifiable, fiber-coupled distributed-feedback semiconductor lasers.

  11. Optical logic and signal processing using a semiconductor laser diode-based optical bistability device

    NASA Astrophysics Data System (ADS)

    Zhang, Yuancheng; Song, Qian; He, Shaowei

    1995-02-01

    Using an optical fibre-coupled semiconductor laser diode OBD with output feedback pumping operation in 5 modes (differential gain, bistability, zero-bias, inverted differential gain, and inverted bistability) has been realized respectively, and 5 elementary optical logic functions (AND, OR, NOT, NAND, and NOR) and some optical signal processing such as limiting, reshaping, and triggering have been implemented.

  12. Switchable dual-wavelength fiber laser based on semiconductor optical amplifier and polarization-maintaining fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Feng, Suchun; Xu, Ou; Lu, Shaohua; Ren, Wenhua; Jian, Shuisheng

    2008-12-01

    Switchable dual-wavelength with orthogonal polarizations fiber laser based on semiconductor optical amplifier (SOA) and polarization-maintaining fiber Bragg grating (PMFBG) at room temperature is proposed. Owing to the polarization dependent loss of the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting the polarization controller (PC). The amplitude variation in nearly half an hour is less than 0.1 dB for both wavelengths, which is more stable than that of erbium doped fiber (EDF)-based laser with similar configuration.

  13. Guiding effect of quantum wells in semiconductor lasers

    SciTech Connect

    Aleshkin, V Ya; Dikareva, Natalia V; Dubinov, A A; Zvonkov, B N; Karzanova, Maria V; Kudryavtsev, K E; Nekorkin, S M; Yablonskii, A N

    2013-05-31

    The guiding effect of InGaAs quantum wells in GaAs- and InP-based semiconductor lasers has been studied theoretically and experimentally. The results demonstrate that such waveguides can be effectively used in laser structures with a large refractive index difference between the quantum well material and semiconductor matrix and a large number of quantum wells (e.g. in InP-based structures). (semiconductor lasers. physics and technology)

  14. Chaos synchronization based on a continuous chaos control method in semiconductor lasers with optical feedback.

    PubMed

    Murakami, A; Ohtsubo, J

    2001-06-01

    Chaos synchronization using a continuous chaos control method was studied in two identical chaotic laser systems consisting of semiconductor lasers and optical feedback from an external mirror. Numerical calculations for rate equations indicate that the stability of chaos synchronization depends significantly on the external mirror position. We performed a linear stability analysis for the rate equations. Our results show that the stability of the synchronization is much influenced by the mode interaction between the relaxation oscillation frequency of the semiconductor laser and the external cavity frequency. Due to this interaction, an intensive mode competition between the two frequencies destroys the synchronization, but stable synchronization can be achieved when the mode competition is very weak.

  15. Semiconductor processing with excimer lasers

    SciTech Connect

    Young, R.T.; Narayan, J.; Christie, W.H.; van der Leeden, G.A.; Rothe, D.E.; Cheng, L.J.

    1983-01-01

    The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeCl and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at uv and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCl laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCl laser annealed region are 2 to 3 orders of magnitude lower than that obtained from ruby or Nd:YAG lasers. All these results seem to suggest that XeCl lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications.

  16. Theory, Modeling, and Simulation of Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    Semiconductor lasers play very important roles in many areas of information technology. In this talk, I will first give an overview of semiconductor laser theory. This will be followed by a description of different models and their shortcomings in modeling and simulation. Our recent efforts in constructing a fully space and time resolved simulation model will then be described. Simulation results based on our model will be presented. Finally the effort towards a self-consistent and comprehensive simulation capability for the opto-electronics integrated circuits (OEICs) will be briefly reviewed.

  17. Diode-laser based scanning laser thermoelectric microscope for thermal diffusivity characterization of thin films on semiconductor substrates

    SciTech Connect

    Borca-Tasciuc, T.; Chen, G.

    1999-07-01

    This work presents new experimental results in the characterization of thermophysical properties for dielectric thin films on semiconductor substrates using the Scanning Laser Thermoelectric Microscope (SLTM) measurement technique. The new improved SLTM employs a modulated laser beam from a 1.55 {micro}m IR diode laser. The laser is used to create a micro-scale thermal wave in the film by focusing the light through the substrate. At this laser wavelength, the technique can be used to determine the thermal diffusivity for films deposited on semiconductor substrates with the band-gap larger than 0.8eV. The generated thermal wave is detected by a fast responding thermocouple formed between the film surface and the tip of a sharp probe. By scanning the laser beam around the thermocouple, the amplitude and phase distributions of the thermal wave are obtained. The film thermal diffusivity is obtained by fitting the detected phase profile of the thermal wave with a three-dimensional heat conduction model. Experimental results are presented for a film-on-substrate system composed of a two-layer thin film on the silicon substrate. The two-layer film is a 4.65{micro}m silicon dioxide film on which a 100nm thick gold film is deposited in order to provide an absorption layer for the laser light and also to facilitate the thermoelectric detection of the thermal wave.

  18. Semiconductor laser self-mixing micro-vibration measuring technology based on Hilbert transform

    NASA Astrophysics Data System (ADS)

    Tao, Yufeng; Wang, Ming; Xia, Wei

    2016-06-01

    A signal-processing synthesizing Wavelet transform and Hilbert transform is employed to measurement of uniform or non-uniform vibrations in self-mixing interferometer on semiconductor laser diode with quantum well. Background noise and fringe inclination are solved by decomposing effect, fringe counting is adopted to automatic determine decomposing level, a couple of exact quadrature signals are produced by Hilbert transform to extract vibration. The tempting potential of real-time measuring micro vibration with high accuracy and wide dynamic response bandwidth using proposed method is proven by both simulation and experiment. Advantages and error sources are presented as well. Main features of proposed semiconductor laser self-mixing interferometer are constant current supply, high resolution, simplest optical path and much higher tolerance to feedback level than existing self-mixing interferometers, which is competitive for non-contact vibration measurement.

  19. Mid-IR semiconductor lasers for chemical sensing

    NASA Technical Reports Server (NTRS)

    Hill, C. J.; Yang, R. Q.

    2003-01-01

    The development of mid-IR semiconductor diode lasers based on type-II interband cascade structures is presented. How these diode lasers can be developed to meet the requirements in chemical sensing applications is discussed.

  20. Tunable Infrared Semiconductor Lasers

    DTIC Science & Technology

    2013-12-20

    is a thulium fiber laser that has output of 20Watts at 1.908 µm with a collimated output beam diameter of about 5 mm. With a cylindrical lens, a...the device onto a copper heat sink and then to the cold finger of liquid nitrogen Dewar. In characterization, a thulium fiber laser at 1.908 nm

  1. Electron beam pumped semiconductor laser

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  2. Blue and UV Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Krukowski, S.; Skierbiszewski, C.; Perlin, P.; Leszczynski, M.; Bockowski, M.; Porowski, S.

    2006-04-01

    Despite many technological difficulties the group III nitrides: GaN, AlN and InN and their alloys are primary candidates for electro-optical coherent light sources. In the recent years the research and technology of the nitride based continuous wave (CW) laser diodes (LDs) led to creation of blue-violet coherent light sources of power up to 200 mW. The progress has been attained by using various ways to attack the main obstacles in the technology of these devices such as insufficient size of high quality lattice matched substrates, low p-doping efficiency of Mg acceptor, poor contact to p-type semiconductor and low efficiency of radiative recombination. The two different approaches were used to overcome the substrate problem: hetero-epitaxy and homoepitaxy. Homoepitaxy used high pressure GaN high quality crystals. Heteroepitaxy used sapphire, SiC or GaAs substrates and very sophisticated techniques of reduction of the dislocation density. The low p-doping efficiency by using Mg acceptor is related to creation of Mg--H complexes due to hydrogen presence during the growth of laser diode quantum structures. In addition, Mg acceptor has low efficiency due to its high energy. High Mg concentrations can be obtained by using either MOCVD or ammonia source MBE growth. An alternative route is to use hydrogen-free plasma activated MBE (PA-MBE) method. The recent advances and the prospects of both approaches will be discussed. Solid AlGaInN solution offers a possibility to cover wide spectral range, starting from near UV to blue, green and red. Arsenide based laser diodes (LDs) are efficient coherent red light sources. Therefore, nitride based LDs are considered to be devices of choice for green, blue and UV spectral range. So far only blue and violet laser has been realized. The progress toward green and UV lasers is far less spectacular. The results in all these areas and future prospects will be discussed.

  3. Frequency-modulated, tunable, semiconductor-optical-amplifier-based fiber ring laser for linewidth and line shape control.

    PubMed

    Girard, Simon Lambert; Chen, Hongxin; Schinn, Gregory W; Piché, Michel

    2008-08-15

    We report how the linewidth and line shape of a tunable semiconductor-optical-amplifier-based fiber ring laser can be actively adjusted by applying an intracavity frequency modulation to the laser. Frequency-modulated laser operation is achieved by driving the phase modulator frequency close to the cavity axial-mode spacing, leading to a constant-amplitude laser output having a periodically varying instantaneous frequency. The resulting linewidth varies proportionally with the inverse of the frequency detuning, and it is adjustable from submegahertz to over more than 5 GHz. By appropriate selection of the modulating waveform we have synthesized a near-Gaussian output line shape; other line shapes can be produced by modifying the modulating waveform. Experimental observations are in good agreement with a simple model.

  4. Slow Light Semiconductor Laser

    DTIC Science & Technology

    2015-02-02

    Painter, “Nonlinear response of silicon photonic crystal microresonators excited via an integrated waveguide and fiber taper,” Opt. Express, vol. 13, pp...exceeding 106 (figure 2g), which represent record high Q for 1D photonic crystal waveguide resonators on Si-on-insulator (SOI). In the hybrid lasers, the...1 million) of photonic crystal nanocavities. Optics Express 14:1996–2002. [14] Akahane Y, Asano T, Song BS, Noda S (2003) High-Q photonic nanocavity

  5. Optical clock division based on dual-wavelength mode-locked semiconductor fiber ring laser.

    PubMed

    Zhang, Weiwei; Sun, Junqiang; Wang, Jian; Zhang, Xingliang; Huang, Dexiu

    2008-07-21

    We have reported the optical clock division utilizing an injected mode-locked fiber ring laser incorporating semiconductor optical amplifiers (SOAs) and a dispersion compensation fiber (DCF). The clock division is mainly caused by the modulation competition between two wavelength components while both of them satisfy the harmonic mode-locking condition at the newly generated frequency. Stable second, third, and fourth clock divisions are obtained by properly adjusting the polarization controllers inside the ring cavity when a 10-GHz clock signal without any sub-harmonic frequency component is injected into the cavity. The radio-frequency spectra show good qualities of the obtained clock division trains.

  6. Selection of modes in transverse-mode waveguides for semiconductor lasers based on asymmetric heterostructures

    SciTech Connect

    Slipchenko, S. O. Bondarev, A. D.; Vinokurov, D. A.; Nikolaev, D. N.; Fetisova, N. V.; Sokolova, Z. N.; Pikhtin, N. A.; Tarasov, I. S.

    2009-01-15

    Asymmetric Al{sub 0.3}Ga{sub 0.7}As/GaAs/InGaAs heterostructures with a broadened waveguide produced by the method of MOCVD epitaxy are studied. It is established that the precision shift of the active region to one of the cladding layers ensures the generation of the chosen mode of high order in the transverse broadened waveguide. It is experimentally established that this shift brings about an increase in internal optical losses and a decrease in the internal quantum efficiency of stimulated emission. It is shown experimentally that the shift of the active region to the n-type cladding layer governs the sublinear form of the power-current characteristic for semiconductor lasers; in the case of a shift of the active region towards the p-type cladding layer, the laser diodes demonstrated a linear dependence of optical power on the pump current in the entire range of pump currents.

  7. Semiconductor laser device

    SciTech Connect

    Namizaki, H.; Susaki, W.; Takamiya, S.; Tanaka, T.

    1981-07-07

    A first N-AlGaAs and a second N-GaAs layer are successively grown on an I-GaAs substrate. A third N-AlGaAs, a fourth P-AlGaAs and a fifth N-GaAs layer superpose one another on the second layer except for one lateral portion. Those portions of the five layers remote from the exposed second layer portion are changed into a P+ type and surrounded by a P zone. A positive and a negative electrode are located on the fifth layer and the exposed second layer portion, respectively. The negative electrode is nearest to a laser region located in the second layer and can be secured to a heat sink.

  8. TUNABLE RING LASER BASED ON A SEMICONDUCTOR OPTICAL AMPLIFIER AT 1300 NM USING A SIMPLE WAVELENGTH SELECTION FILTER

    PubMed Central

    Jeon, Mansik; Kim, Jeehyun; Song, Jae-Won; Lee, Ho; Choi, Sanghoon; Nelson, J. Stuart

    2009-01-01

    A simple, compact, and low cost tunable ring laser with a commercial semiconductor optical amplifier (SOA) was demonstrated. The tunable ring laser is based on an external wavelength filter cavity that is analogous with the Littman configuration with a diffraction grating, a mirror, and a simple slit. The unique structural advantage of this new system is that the slit is displaced to select a desired wavelength instead of tilting the mirror as in the Littman configuration. This allows easy control over the selected wavelength by the translating action of the slit. The full width half maximum (FWHM) wavelength turning range is 45 nm, and the wavelength resolution is about 2 pm. The demonstrated tunable ring laser has 2 mW output power. The side mode suppression ratios is 70–73 dB. PMID:20539831

  9. Optical complexity in external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Rondoni, Lamberto; Ariffin, M. R. K.; Varatharajoo, Renuganth; Mukherjee, Sayan; Palit, Sanjay K.; Banerjee, Santo

    2017-03-01

    In this article, the window based complexity and output modulation of a time delayed chaotic semiconductor laser (SL) model has been investigated. The window based optical complexity (OC), is measured by introducing the recurrence sample entropy (SampEn). The analysis has been done without and in the presence of external noise. The significant changes in the dynamics can be observed under induced noise with weak strength. It has also been found that there is a strong positive correlation between the output power and the complexity of the system with various sets of parameters. The laser intensity, as well as the OC can be increased with the incremental noise strength and the associated system parameters. Thus, optical complexity quantifies the system dynamics and its instabilities, since is strongly correlated with the laser outputs. This analysis can be applied to measure the laser instabilities and modulation of output power.

  10. EDITORIAL: Semiconductor lasers: the first fifty years Semiconductor lasers: the first fifty years

    NASA Astrophysics Data System (ADS)

    Calvez, S.; Adams, M. J.

    2012-09-01

    Anniversaries call for celebrations. Since it is now fifty years since the first semiconductor lasers were reported, it is highly appropriate to celebrate this anniversary with a Special Issue dedicated to the topic. The semiconductor laser now has a major effect on our daily lives since it has been a key enabler in the development of optical fibre communications (and hence the internet and e-mail), optical storage (CDs, DVDs, etc) and barcode scanners. In the early 1960s it was impossible for most people (with the exception of very few visionaries) to foresee any of these future developments, and the first applications identified were for military purposes (range-finders, target markers, etc). Of course, many of the subsequent laser applications were made possible by developments in semiconductor materials, in the associated growth and fabrication technology, and in the increased understanding of the underlying fundamental physics. These developments continue today, so that the subject of semiconductor lasers, although mature, is in good health and continues to grow. Hence, we can be confident that the pervasive influence of semiconductor lasers will continue to develop as optoelectronics technology makes further advances into other sectors such as healthcare, security and a whole host of applications based on the global imperatives to reduce energy consumption, minimise environmental impact and conserve resources. The papers in this Special Issue are intended to tell some of the story of the last fifty years of laser development as well as to provide evidence of the current state of semiconductor laser research. Hence, there are a number of papers where the early developments are recalled by authors who played prominent parts in the story, followed by a selection of papers from authors who are active in today's exciting research. The twenty-fifth anniversary of the semiconductor laser was celebrated by the publication of a number of papers dealing with the early

  11. Optical isolator for semiconductor lasers.

    PubMed

    Kuwahara, H

    1980-01-15

    An optical isolator for semiconductor lasers, consisting of a polarizer and a quarterwave plate, was investigated experimentally. It was assembled in a compact laser-to-fiber coupling module. Experiment showed forward loss of 1.15 dB, backward loss of 24.8 dB, and rotative tolerance of 2.4 deg for 1 dB down. The length of the module is 43.2 mm. The coupling efficiency to a graded-index multimode fiber is 37.5%. The extinction ratio is improved by 6.75 dB. The suppression effect on the influence of reflected light was investigated, using the assembled module.

  12. Tunable and switchable multi-wavelength fiber laser based on semiconductor optical amplifier and twin-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Kim, Bongkyun; Han, Jihee; Chung, Youngjoo

    2012-02-01

    Multi-wavelength fiber lasers have attracted a lot of interest, recently, because of their potential applications in wavelength-division-multiplexing (WDM) systems, optical fiber sensing, and fiber-optics instruments, due to their numerous advantages such as multiple wavelength operation, low cost, and compatibility with the fiber optic systems. Semiconductor optical amplifier (SOA)-based multi-wavelength fiber lasers exhibit stable operation because of the SOA has the property of primarily inhomogeneous broadening and thus can support simultaneous oscillation of multiple lasing wavelengths. In this letter, we propose and experimentally demonstrate a switchable multi-wavelength fiber laser employing a semiconductor optical amplifier and twin-core photonic crystal fiber (TC-PCF) based in-line interferometer comb filter. The fabricated two cores are not symmetric due to the associated fiber fabrication process such as nonuniform heat gradient in furnace and asymmetric microstructure expansion during the gas pressurization which results in different silica strut thickness and core size. The induced asymmetry between two cores considerably alters the linear power transfer, by seriously reducing it. These nominal twin cores form effective two optical paths and associated effective refractive index difference. The in-fiber comb filter is effectively constructed by splicing a section of TC-PCF between two single mode fibers (SMFs). The proposed laser can be designed to operate in stable multi-wavelength lasing states by adjusting the states of the polarization controller (PC). The lasing modes are switched by varying the state of PC and the change is reversible. In addition, we demonstrate a tunable multi-wavelength fiber laser operation by applying temperature changes to TC-PCF in the multi-channel filter.

  13. Characterization of wavelength-swept active mode locking fiber laser based on reflective semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Lee, Hwi Don; Lee, Ju Han; Yung Jeong, Myung; Kim, Chang-Seok

    2011-07-01

    The static and dynamic characteristics of a wavelength-swept active mode locking (AML) fiber laser are presented in both the time-region and wavelength-region. This paper shows experimentally that the linewidth of a laser spectrum and the bandwidth of the sweeping wavelength are dependent directly on the length and dispersion of the fiber cavity as well as the modulation frequency and sweeping rate under the mode-locking condition. To achieve a narrower linewidth, a longer length and higher dispersion of the fiber cavity as well as a higher order mode locking condition are required simultaneously. For a broader bandwidth, a lower order of the mode locking condition is required using a lower modulation frequency. The dynamic sweeping performance is also analyzed experimentally to determine its applicability to optical coherence tomography imaging. It is shown that the maximum sweeping rate can be improved by the increased free spectral range from the shorter length of the fiber cavity. A reflective semiconductor optical amplifier (RSOA) was used to enhance the modulation and dispersion efficiency. Overall a triangular electrical signal can be used instead of the sinusoidal signal to sweep the lasing wavelength at a high sweeping rate due to the lack of mechanical restrictions in the wavelength sweeping mechanism.

  14. Tunable high-power narrow-linewidth semiconductor laser based on an external-cavity tapered amplifier.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Holm, Jesper; Pedersen, Christian; Andersen, Peter Eskil; Erbert, Götz; Sumpf, Bernd; Petersen, Paul Michael

    2005-12-26

    A high-power narrow-linewidth laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The external cavity laser system uses a new tapered amplifier with a super-large optical-cavity (SLOC) design that leads to improved performance of the external cavity diode lasers. The laser system is tunable over a 29 nm range centered at 802 nm. As high as 1.95 W output power is obtained at 803.84 nm, and an output power above 1.5 W is achieved from 793 to 812 nm at operating current of 3.0 A. The emission linewidth is below 0.004 nm and the beam quality factor M2 is below 1.3 over the 29 nm tunable range. As an example of application, the laser system is used as a pump source for the generation of 405 nm blue light by single-pass frequency doubling in a periodically poled KTiOPO4. An output power of 24 mW at 405 nm, corresponding to a conversion efficiency of 0.83%/W is attained.

  15. Semiconductor disk laser-pumped subpicosecond holmium fibre laser

    SciTech Connect

    Chamorovskiy, A Yu; Marakulin, A V; Leinonen, T; Kurkov, Andrei S; Okhotnikov, Oleg G

    2012-01-31

    The first passively mode-locked holmium fibre laser has been demonstrated, with a semiconductor saturable absorber mirror (SESAM) as a mode locker. Semiconductor disk lasers have been used for the first time to pump holmium fibre lasers. We obtained 830-fs pulses at a repetition rate of 34 MHz with an average output power of 6.6 mW.

  16. REVIEW ARTICLE: Harmonically mode-locked semiconductor-based lasers as high repetition rate ultralow noise pulse train and optical frequency comb sources

    NASA Astrophysics Data System (ADS)

    Quinlan, F.; Ozharar, S.; Gee, S.; Delfyett, P. J.

    2009-10-01

    Recent experimental work on semiconductor-based harmonically mode-locked lasers geared toward low noise applications is reviewed. Active, harmonic mode-locking of semiconductor-based lasers has proven to be an excellent way to generate 10 GHz repetition rate pulse trains with pulse-to-pulse timing jitter of only a few femtoseconds without requiring active feedback stabilization. This level of timing jitter is achieved in long fiberized ring cavities and relies upon such factors as low noise rf sources as mode-lockers, high optical power, intracavity dispersion management and intracavity phase modulation. When a high finesse etalon is placed within the optical cavity, semiconductor-based harmonically mode-locked lasers can be used as optical frequency comb sources with 10 GHz mode spacing. When active mode-locking is replaced with regenerative mode-locking, a completely self-contained comb source is created, referenced to the intracavity etalon.

  17. Frequency modulation of semiconductor disk laser pulses

    SciTech Connect

    Zolotovskii, I O; Korobko, D A; Okhotnikov, O G

    2015-07-31

    A numerical model is constructed for a semiconductor disk laser mode-locked by a semiconductor saturable absorber mirror (SESAM), and the effect that the phase modulation caused by gain and absorption saturation in the semiconductor has on pulse generation is examined. The results demonstrate that, in a laser cavity with sufficient second-order dispersion, alternating-sign frequency modulation of pulses can be compensated for. We also examine a model for tuning the dispersion in the cavity of a disk laser using a Gires–Tournois interferometer with limited thirdorder dispersion. (control of radiation parameters)

  18. Semiconductor Lasers and Their Application in Optical Fiber Communication.

    ERIC Educational Resources Information Center

    Agrawal, Govind P.

    1985-01-01

    Working principles and operating characteristics of the extremely compact and highly efficient semiconductor lasers are explained. Topics include: the p-n junction; Fabry-Perot cavity; heterostructure semiconductor lasers; materials; emission characteristics; and single-frequency semiconductor lasers. Applications for semiconductor lasers include…

  19. Semiconductor laser applications in rheumatology

    NASA Astrophysics Data System (ADS)

    Pascu, Mihail-Lucian; Suteanu, S.

    1996-01-01

    Two types of laser diode (LD) based equipment for rheumatology are introduced. The first is a portable device which contains single LD emitting at 890 nm laser pulses (time full width 100 nsec) of reprate tunable within (0.5 - 1.5) kHz; the laser beam average power is 0.7 mW at 1 kHz reprate. The second is computer controlled, contains one HeNe laser and 5 LD allowing 6 modes of patient irradiation (placebo effect evaluation included). HeNe laser works in cw at 632.8 nm; the LD works each as described for the portable equipment. HeNe and LD beams are superposed so that HeNe laser spot in the irradiation plane has a 60 mm diameter and the LD spots covers a 50 mm diameter disc centered on the HeNe laser spot. Clinical applications using the second type of equipment are reported; 1287 patients were treated between October 1991 and October 1994. Female/male ratio was 4:1 and their age distribution was between 18 and 85 years. The average number of exposures was 10 and the mean exposure time was 7 minutes. Studies were made on the treatment of rheumatoid arthritis, seronegative arthritis, degenerative joint diseases, abarticular rheumatism, osteoporosis pain and pains and edema after fractures.

  20. Dissipative Phase Solitons in Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Gustave, F.; Columbo, L.; Tissoni, G.; Brambilla, M.; Prati, F.; Kelleher, B.; Tykalewicz, B.; Barland, S.

    2015-07-01

    We experimentally demonstrate the existence of nondispersive solitary waves associated with a 2 π phase rotation in a strongly multimode ring semiconductor laser with coherent forcing. Similarly to Bloch domain walls, such structures host a chiral charge. The numerical simulations based on a set of effective Maxwell-Bloch equations support the experimental evidence that only one sign of chiral charge is stable, which strongly affects the motion of the phase solitons. Furthermore, the reduction of the model to a modified Ginzburg-Landau equation with forcing demonstrates the generality of these phenomena and exposes the impact of the lack of parity symmetry in propagative optical systems.

  1. Third order mode optically pumped semiconductor laser

    NASA Astrophysics Data System (ADS)

    De Rossi, A.; Semaltianos, N.; Chirlias, E.; Vinter, B.; Ortiz, V.; Berger, V.

    2002-06-01

    Lasing action on a third order waveguide mode is demonstrated at room temperature under optical pumping, in a specifically designed quantum well laser structure. The AlGaAs heterostructure involves barriers which ensure that the third order waveguide mode has a higher overlap with the single quantum well emitter than the fundamental mode. Third order mode operation of a laser structure opens the way to modal phase matched parametric down conversion inside the semiconductor laser itself. It is a first step towards the realization of semiconductor twin photon laser sources, needed for quantum information experiments.

  2. A novel approach for generating flat optical frequency comb based on externally injected gain-switching distributed feedback semiconductor laser

    NASA Astrophysics Data System (ADS)

    Zhu, Huatao; Wang, Rong; Pu, Tao; Xiang, Peng; Zheng, Jilin; Fang, Tao

    2017-02-01

    In this paper, a novel approach for generating flat optical frequency comb (OFC) based on externally injected gain-switched distributed feedback (DFB) semiconductor laser is proposed and experimentally demonstrated. In the proposed system, the flatness, the number of OFC spectral lines, and the spectral line to background noise ratio can be tuned to their optimized values by adjusting the current of the modulation signal, the injection ratio and the detuning frequency. Since the frequency of the modulation signal decides the frequency spacing of the output spectral lines, OFC spectral lines of different spacing can be achieved. In the experiment, 10 spectral lines with 1.5 dB power variation are demonstrated to verify the proposed approach. In addition, the expansion of the spectral line is investigated.

  3. High power semiconductor lasers for deep space communications

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1981-01-01

    The parameters of semiconductor lasers pertaining to their application as optical emitters are discussed. Several methods to overcome their basic disadvantage, which is the low level of powers they emit, are reviewed. Most of these methods are based on a coherent power combining of several lasers.

  4. Investigating the effects of capping layer on optical gain of nitride based semiconductor nanostructure lasers

    NASA Astrophysics Data System (ADS)

    Annabi Milani, E.; Mohadesi, V.; Asgari, A.

    2017-04-01

    In this study, the effects of GaN capping layer on the behaviour of AlGaN/GaN nanostructure based laser is considered. We have employed the self-consistent solution of Poisson and Schrodinger equations for calculation of the energy levels, wave functions and conduction and valance bands profile. The impact of different thicknesses of the capping layer has been studied for sheet carrier density, then on optical gain. The results indicate that, by increasing the thickness of the cap layer, the optical gain decreases.

  5. A 1.33 µm picosecond pulse generator based on semiconductor disk mode-locked laser and bismuth fiber amplifier.

    PubMed

    Heikkinen, Juuso; Gumenyuk, Regina; Rantamäki, Antti; Leinonen, Tomi; Melkumov, Mikhail; Dianov, Evgeny M; Okhotnikov, Oleg G

    2014-05-19

    We demonstrate that a combination of ultrafast wafer bonded semiconductor disk laser and a bismuth-doped fiber amplifier provides an attractive design for high power 1.33 µm tandem hybrid systems. Over 0.5 W of average output power was achieved at a repetition rate of 827 MHz that corresponds to a pulse energy of 0.62 nJ.

  6. Semiconductor laser gyro with optical frequency dithering

    SciTech Connect

    Prokof'eva, L P; Sakharov, V K; Shcherbakov, V V

    2014-04-28

    The semiconductor laser gyro is described, in which the optical frequency dithering implemented by intracavity phase modulation suppresses the frequency lock-in and provides the interference of multimode radiation. The sensitivity of the device amounted to 10–20 deg h{sup -1}. (laser gyroscopes)

  7. Semiconductor laser with multiple lasing wavelengths

    DOEpatents

    Fischer, Arthur J.; Choquette, Kent D.; Chow, Weng W.

    2003-07-29

    A new class of multi-terminal vertical-cavity semiconductor laser components has been developed. These multi-terminal laser components can be switched, either electrically or optically, between distinct lasing wavelengths, or can be made to lase simultaneously at multiple wavelengths.

  8. Synchronization of semiconductor laser arrays with 2D Bragg structures

    NASA Astrophysics Data System (ADS)

    Baryshev, V. R.; Ginzburg, N. S.

    2016-08-01

    A model of a planar semiconductor multi-channel laser is developed. In this model two-dimensional (2D) Bragg mirror structures are used for synchronizing radiation of multiple laser channels. Coupling of longitudinal and transverse waves can be mentioned as the distinguishing feature of these structures. Synchronization of 20 laser channels is demonstrated with a semi-classical approach based on Maxwell-Bloch equations.

  9. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    SciTech Connect

    Deri, R J

    2011-01-03

    Solid-state lasers have been demonstrated as attractive drivers for inertial confinement fusion on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) and at the Omega Facility at the Laboratory for Laser Energetics (LLE) in Rochester, NY. For power plant applications, these lasers must be pumped by semiconductor diode lasers to achieve the required laser system efficiency, repetition rate, and lifetime. Inertial fusion energy (IFE) power plants will require approximately 40-to-80 GW of peak pump power, and must operate efficiently and with high system availability for decades. These considerations lead to requirements on the efficiency, price, and production capacity of the semiconductor pump sources. This document provides a brief summary of these requirements, and how they can be met by a natural evolution of the current semiconductor laser industry. The detailed technical requirements described in this document flow down from a laser ampl9ifier design described elsewhere. In brief, laser amplifiers comprising multiple Nd:glass gain slabs are face-pumped by two planar diode arrays, each delivering 30 to 40 MW of peak power at 872 nm during a {approx} 200 {micro}s quasi-CW (QCW) pulse with a repetition rate in the range of 10 to 20 Hz. The baseline design of the diode array employs a 2D mosaic of submodules to facilitate manufacturing. As a baseline, they envision that each submodule is an array of vertically stacked, 1 cm wide, edge-emitting diode bars, an industry standard form factor. These stacks are mounted on a common backplane providing cooling and current drive. Stacks are conductively cooled to the backplane, to minimize both diode package cost and the number of fluid interconnects for improved reliability. While the baseline assessment in this document is based on edge-emitting devices, the amplifier design does not preclude future use of surface emitting diodes, which may offer appreciable future cost reductions and

  10. Advances in high power semiconductor diode lasers

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  11. Closure of incision in cataract surgery in-vivo using a temperature controlled laser soldering system based on a 1.9μm semiconductor laser

    NASA Astrophysics Data System (ADS)

    Gabay, Ilan; Basov, Svetlana; Varssano, David; Barequet, Irina; Rosner, Mordechai; Rattunde, Marcel; Wagner, Joachim; Platkov, Max; Harlev, Mickey; Rossman, Uri; Katzir, Abraham

    2016-03-01

    In phacoemulsification-based cataract surgery, a corneal incision is made and is then closed by hydration of the wound lips, or by suturing. We developed a system for sealing such an incision by soldering with a semiconductor disk laser (λ=1.9μm), under close temperature control. The goal was to obtain stronger and more watertight adhesion. The system was tested on incisions in the corneas of 15 eyes of pigs, in-vivo. Optical Coherent Tomography (OCT) and histopathologic examination showed little thermal damage and good apposition. The measured average burst pressure was 1000+/-30mmHg. In the future, this method wound may replace suturing of corneal wounds, including in traumatic corneal laceration and corneal transplantation.

  12. Laser Assisted Semiconductor Device Processing

    DTIC Science & Technology

    1980-11-30

    In strongly absorbing semiconductors, the dominant absorption mechanism at frequencies higher than the bandgap frequency is interband transitions. The...current). The solution for miconductors. In strongly absorbing semiconductors, the n(x,t ) is a closed-form expression consisting of complemen- dominant 0...representative profles are shown in Fis. $-12. o -- For Nd: YAG in silicon. E, _0.99hv and the profiks are therefore and-gap recombination dominated

  13. Phase Instability in Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Gil, L.; Lippi, G. L.

    2014-11-01

    For many years, the apparent absence of a phase instability has characterized lasers as peculiar nonlinear oscillators. We show that this unusual feature is solely due to the approximations used in writing the standard models. A new, careful derivation of the fundamental equations, based on codimension 2 bifurcation theory, shows the possible existence of dynamical regimes displaying either a pure phase instability, or mixed phase-amplitude turbulence. A comparison to existing experimental results convincingly shows that the Benjamin-Feir instability, common to all nonlinear wave problems, is a fundamental, satisfactory interpretation for their deterministic multimode dynamics.

  14. Whispering-gallery-mode-resonator-based ultranarrow linewidth external-cavity semiconductor laser.

    PubMed

    Liang, W; Ilchenko, V S; Savchenkov, A A; Matsko, A B; Seidel, D; Maleki, L

    2010-08-15

    We demonstrate a miniature self-injection locked distributed-feedback laser using resonant optical feedback from a high-Q crystalline whispering-gallery-mode resonator. The linewidth reduction factor is greater than 10,000, with resultant instantaneous linewidth of less than 200 Hz. The minimal value of the Allan deviation for the laser-frequency stability is 3 x 10(-12) at the integration time of 20 micros. The laser possesses excellent spectral purity and good long-term stability.

  15. Injection-locked semiconductor laser-based frequency comb for modulation applications in RF analog photonics.

    PubMed

    Sarailou, Edris; Delfyett, Peter

    2016-07-01

    A linearized intensity modulator for periodic and pulsed light is proposed and demonstrated. The free carrier plasma effect has been used to modulate the refractive index of the phase section of a three-section mode-locked laser. If injection locked, the modulation induces an arcsine phase response on the three-section mode-locked laser. By introducing this mode-locked laser into a Mach-Zehnder interferometer biased at quadrature, one can realize a true linear intensity modulation. This novel laser suppresses any unwanted amplitude modulation and increases the performance of the linearized intensity modulator. Experimental results have provided a record low static Iπ of 0.39 mA and a spur-free dynamic range of 75  dB.Hz2/3.

  16. Fiber-based multiple-beam reflection interferometer for single-longitudinal-mode generation in fiber laser based on semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Terentyev, V. S.; Simonov, V. A.; Babin, S. A.

    2017-02-01

    A technique of single-longitudinal-mode selection in a fiber laser by means of a fiber multiple-beam reflection interferometer (FRI) has been experimentally demonstrated for the first time. The laser is based on a semiconductor optical amplifier placed in a linear fiber cavity formed by a fiber Bragg grating (FBG), and the FRI generates at 1529.24 nm with output power of 1 mW in single-frequency regime with a linewidth of about 217 kHz and polarization extinction ratio of  >30 dB. The FRI technique potentially enables fast tuning (within the FBG bandwidth of ~0.9 nm in our case) by varying the base length of the FRI that can be used in a number of practical applications.

  17. Turbulent chimeras in large semiconductor laser arrays

    NASA Astrophysics Data System (ADS)

    Shena, J.; Hizanidis, J.; Kovanis, V.; Tsironis, G. P.

    2017-02-01

    Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure.

  18. Turbulent chimeras in large semiconductor laser arrays

    PubMed Central

    Shena, J.; Hizanidis, J.; Kovanis, V.; Tsironis, G. P.

    2017-01-01

    Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure. PMID:28165053

  19. Turbulent chimeras in large semiconductor laser arrays.

    PubMed

    Shena, J; Hizanidis, J; Kovanis, V; Tsironis, G P

    2017-02-06

    Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure.

  20. High frequency optoelectronic oscillators based on the optical feedback of semiconductor mode-locked laser diodes.

    PubMed

    Haji, Mohsin; Hou, Lianping; Kelly, Anthony E; Akbar, Jehan; Marsh, John H; Arnold, John M; Ironside, Charles N

    2012-01-30

    Optical self seeding feedback techniques can be used to improve the noise characteristics of passively mode-locked laser diodes. External cavities such as fiber optic cables can increase the memory of the phase and subsequently improve the timing jitter. In this work, an improved optical feedback architecture is proposed using an optical fiber loop delay as a cavity extension of the mode-locked laser. We investigate the effect of the noise reduction as a function of the loop length and feedback power. The well known composite cavity technique is also implemented for suppressing supermode noise artifacts presented due to harmonic mode locking effects. Using this method, we achieve a record low radio frequency linewidth of 192 Hz for any high frequency (>1 GHz) passively mode-locked laser to date (to the best of the authors' knowledge), making it promising for the development of high frequency optoelectronic oscillators.

  1. Chirp evaluation of semiconductor DFB lasers through a simple Interferometry-Based (IB) technique.

    PubMed

    Nanni, Jacopo; Barbiroli, Marina; Fuschini, Franco; Masotti, Diego; Polleux, Jean-Luc; Algani, Catherine; Tartarini, Giovanni

    2016-10-01

    Direct modulation of a laser source is often utilized in realizing optical fiber connections where the cost of the entire system must be kept at a low level. An undesired consequence of this choice is the onset of the laser frequency chirp effect, which is detrimental in the case of either digital or analog links, and must be evaluated with precision in order to perform an accurate design of the whole system. Various methods of evaluation of the chirp parameters have been proposed, and the choice among them is typically made on the basis of the laboratory equipment available at the moment. This paper adds a further element to the set of possible choices, since it presents a method for the evaluation of the adiabatic chirp factor in distributed feedback (DFB) laser sources, which exploits a simple interferometric scheme, guarantees low cost, and shows, at the same time, good accuracy of the results.

  2. Broadband terahertz ultrasonic transducer based on a laser-driven piezoelectric semiconductor superlattice.

    PubMed

    Maznev, A A; Manke, Kara J; Lin, Kung-Hsuan; Nelson, Keith A; Sun, Chi-Kuang; Chyi, Jen-Inn

    2012-01-01

    Spectral characteristics of laser-generated acoustic waves in an InGaN/GaN superlattice structure are studied at room temperature. Acoustic vibrations in the structure are excited with a femtosecond laser pulse and detected via transmission of a delayed probe pulse. Seven acoustic modes of the superlattice are detected, with frequencies spanning a range from 0.36 to 2.5THz. Acoustic waves up to ∼2THz in frequency are not significantly attenuated within the transducer which indicates excellent interface quality of the superlattice. The findings hold promise for broadband THz acoustic spectroscopy.

  3. Semiconductor Laser With Multilayer Dielectric Reflector

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1991-01-01

    Multilayer dielectric reflector included in proposed surface-emitting, distributed-feedback, grating semiconductor laser (e.g., a GaAlAs device). Contributes to efficiency and output power of laser by reducing amount of light entering substrate, where wasted by absorption. Index of refraction in reflector sublayers alternates between higher and lower value. Higher value less than effective index of refraction of waveguide layer.

  4. Ferromagnets based on diamond-like semiconductors GaSb, InSb, Ge, and Si supersaturated with manganese or iron impurities during laser-plasma deposition

    SciTech Connect

    Demidov, E. S.; Podol'skii, V. V.; Lesnikov, V. P.; Sapozhnikov, M. V.; Druzhnov, D. M.; Gusev, S. N.; Gribkov, B. A.; Filatov, D. O.; Stepanova, Yu. S.; Levchuk, S. A.

    2008-01-15

    Properties of thin (30-100 nm) layers of diluted magnetic semiconductors based on diamond-like compounds III-V (InSb and GaSb) and elemental semiconductors Ge and Si doped with 3d impurities of manganese and iron up to 15% were measured and discussed. The layers were grown by laser-plasma deposition onto heated single-crystal gallium arsenide or sapphire substrates. The ferromagnetism of layers with the Curie temperature up to 500 K appeared in observations of the ferromagnetic resonance, anomalous Hall effect, and magneto-optic Kerr effect. The carrier mobility of diluted magnetic semiconductors is a hundred times larger than that of the previously known highest temperature magnetic semiconductors, i.e., copper and chromium chalcogenides. The difference between changes in the magnetization with temperature in diluted semiconductors based on III-V, Ge, and Si was discussed. A complex structure of the ferromagnetic resonance spectrum in Si:Mn/GaAs was observed. The results of magnetic-force microscopy showed a weak correlation between the surface relief and magnetic inhomogeneity, which suggests that the ferromagnetism is caused by the 3d-impurity solid solution, rather than ferromagnetic phase inclusions.

  5. Laser-based irradiation apparatus and method to measure the functional dose-rate response of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2008-05-20

    A broad-beam laser irradiation apparatus can measure the parametric or functional response of a semiconductor device to exposure to dose-rate equivalent infrared laser light. Comparisons of dose-rate response from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems can determine if aging has affected the device's overall functionality. The dependence of these changes on equivalent dose-rate pulse intensity and/or duration can be measured with the apparatus. The synchronized introduction of external electrical transients into the device under test can be used to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure while exposing the device to dose-rate equivalent infrared laser light.

  6. Method and system for powering and cooling semiconductor lasers

    SciTech Connect

    Telford, Steven J; Ladran, Anthony S

    2014-02-25

    A semiconductor laser system includes a diode laser tile. The diode laser tile includes a mounting fixture having a first side and a second side opposing the first side and an array of semiconductor laser pumps coupled to the first side of the mounting fixture. The semiconductor laser system also includes an electrical pulse generator thermally coupled to the diode bar and a cooling member thermally coupled to the diode bar and the electrical pulse generator.

  7. Semiconductor Laser Linewidth Measurements for Space Interferometry Applications

    NASA Technical Reports Server (NTRS)

    Dougherty, D. J.; Guttierrez, R. C.; Dubovitsky, S.; Forouhar, S.

    2000-01-01

    Narrow linewidth (<100KHz) semiconductor lasers are expected to be a key technology in NASA's stellar interferometry missions to search for planets around nearby stars. Long coherence length lasers are needed for precise (20 pm to 5 mn) measurements of the optical path difference. This work discusses results using the self-heterodyne delay technique to measure 1.3 micrometer InP based DFB lasers. We will also address practical issues concerning detection and elimination of back reflections, choice of fiber length and resolution, and measurement of laser 1/f and current supply noise.

  8. Ultralow noise miniature external cavity semiconductor laser

    PubMed Central

    Liang, W.; Ilchenko, V. S.; Eliyahu, D.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

    2015-01-01

    Advanced applications in optical metrology demand improved lasers with high spectral purity, in form factors that are small and insensitive to environmental perturbations. While laboratory-scale lasers with extraordinarily high stability and low noise have been reported, all-integrated chip-scale devices with sub-100 Hz linewidth have not been previously demonstrated. Lasers integrated with optical microresonators as external cavities have the potential for substantial reduction of noise. However, stability and spectral purity improvements of these lasers have only been validated with rack-mounted support equipment, assembled with fibre lasers to marginally improve their noise performance. In this work we report on a realization of a heterogeneously integrated, chip-scale semiconductor laser featuring 30-Hz integral linewidth as well as sub-Hz instantaneous linewidth. PMID:26104321

  9. Light sources based on semiconductor current filaments

    DOEpatents

    Zutavern, Fred J.; Loubriel, Guillermo M.; Buttram, Malcolm T.; Mar, Alan; Helgeson, Wesley D.; O'Malley, Martin W.; Hjalmarson, Harold P.; Baca, Albert G.; Chow, Weng W.; Vawter, G. Allen

    2003-01-01

    The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

  10. High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms.

    PubMed

    Santis, Christos Theodoros; Steger, Scott T; Vilenchik, Yaakov; Vasilyev, Arseny; Yariv, Amnon

    2014-02-25

    The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 μm, achieved using a single-mode silicon resonator with Q of 10(6).

  11. Subwavelength metal-optic semiconductor nanopatch lasers.

    PubMed

    Yu, Kyoungsik; Lakhani, Amit; Wu, Ming C

    2010-04-26

    We report on near infrared semiconductor nanopatch lasers with subwavelength-scale physical dimensions (0.019 cubic wavelengths) and effective mode volumes (0.0017 cubic wavelengths). We observe lasing in the two most fundamental optical modes which resemble oscillating electrical and magnetic dipoles. The ultra-small laser volume is achieved with the presence of nanoscale metal patches which suppress electromagnetic radiation into free-space and convert a leaky cavity into a highly-confined subwavelength optical resonator. Such ultra-small lasers with metallodielectric cavities will enable broad applications in data storage, biological sensing, and on-chip optical communication.

  12. Alexandrite laser pumped by semiconductor lasers

    SciTech Connect

    Scheps, R.; Gately, B.M.; Myers, J.F. ); Krasinski, J.S. ); Heller, D.F. )

    1990-06-04

    We report the first operation of a direct diode-pumped tunable chromium-doped solid-state laser. A small alexandrite (Cr:BeAl{sub 2}O{sub 4}) crystal was longitudinally pumped by two visible laser diodes. The threshold pump power was 12 mW using the {ital R}{sub 1} line at 680.4 nm for the pump transition, and the slope efficiency was 25%. The measured laser output bandwidth was 2.1 nm.

  13. Alexandrite laser pumped by semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Scheps, Richard; Gately, Bernard M.; Myers, Joseph F.; Krasinski, Jerzy S.; Heller, Donald F.

    1990-06-01

    We report the first operation of a direct diode-pumped tunable chromium-doped solid-state laser. A small alexandrite (Cr:BeAl2O4) crystal was longitudinally pumped by two visible laser diodes. The threshold pump power was 12 mW using the R1 line at 680.4 nm for the pump transition, and the slope efficiency was 25%. The measured laser output bandwidth was 2.1 nm.

  14. Integrated semiconductor twin-microdisk laser under mutually optical injection

    SciTech Connect

    Zou, Ling-Xiu; Liu, Bo-Wen; Lv, Xiao-Meng; Yang, Yue-De; Xiao, Jin-Long; Huang, Yong-Zhen

    2015-05-11

    We experimentally study the characteristics of an integrated semiconductor twin-microdisk laser under mutually optical injection through a connected optical waveguide. Based on the lasing spectra, four-wave mixing, injection locking, and period-two oscillation states are observed due to the mutually optical injection by adjusting the injected currents applied to the two microdisks. The enhanced 3 dB bandwidth is realized for the microdisk laser at the injection locking state, and photonic microwave is obtained from the electrode of the microdisk laser under the period-two oscillation state. The plentifully dynamical states similar as semiconductor lasers subject to external optical injection are realized due to strong optical interaction between the two microdisks.

  15. Visible-wavelength semiconductor lasers and arrays

    DOEpatents

    Schneider, Jr., Richard P.; Crawford, Mary H.

    1996-01-01

    A visible semiconductor laser. The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1.lambda.) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%.

  16. Semiconductor ring lasers as optical neurons

    NASA Astrophysics Data System (ADS)

    Coomans, W.; Gelens, L.; Mashal, L.; Beri, S.; Van der Sande, G.; Danckaert, J.; Verschaffelt, G.

    2012-06-01

    Semiconductor Ring Lasers (SRLs) are a modern class of semiconductor lasers whose active cavity is characterized by a circular geometry. This enables the laser to support two counterpropagating modes, referred to as the clockwise (CW) and the counterclockwise (CCW) mode. Semiconductor ring lasers have been shown to have a regime of operation in which they are excitable, when the linear coupling between the counterpropagating modes is asymmetric. This can be achieved by increasing the reflection of, for example, the CW mode into the CCW mode. This will stabilize lasing in the CCW mode. In the excitable regime, the SRL will fire optical pulses (spikes) in the CW mode as a response to noise perturbations. In this contribution we experimentally and theoretically characterize these spikes. Our experiments reveal a statistical distribution of the characteristics of the optical pulses that is not observed in regular excitable systems. In particular, an inverse correlation exists between the pulse amplitude and duration. Numerical simulations and an interpretation in an asymptotic phase space confirm and explain these experimentally observed pulse characteristics [L. Gelens et al., Phys. Rev. A 82 063841, 2010]. We will also theoretically consider asymmetric SRLs coupled through a single bus waveguide. This is a first step towards an integrated optical neural network using semiconductor ring lasers as building blocks. We will show that for weak coupling, excitatory excursions still persist due to the similar phase space structure. Moreover, the coupled SRLs can excite pulses in each other and can thus function as communicating neurons [W. Coomans et al., Phys. Rev. E 84 036209, 2011]. This type of neural network can be fully integrated on chip and does not suffer from the drawback of needing extra-cavity measures, such as optical injection or saturable absorbers.

  17. Ultrafast Modulation of Semiconductor Lasers Through a Terahertz Field

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Hughes, Steven; Citrin, David

    1998-01-01

    We demonstrate, by means of numerical simulation, a new mechanism to modulate and switch semiconductor lasers at THz and sub-THz frequency rates. A sinusoidal terahertz field applied to a semiconductor laser heats the electron-hole plasma and consequently modifies the optical susceptibility. This allows an almost linear modulation of the output power of tile semiconductor laser and leads to a faithful reproduction of the terahertz-field waveform in the emitted laser intensity.

  18. Optical communication with semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic; Sun, X.

    1989-01-01

    This interim report describes the progress in the construction of a 220 Mbps Q=4 PPM optical communication system that uses a semiconductor laser as the optical transmitter and an avalanche photodiode (APD) as the photodetector. The transmitter electronics have been completed and contain both GaAs and ECL III IC's. The circuit was able to operate at a source binary data rate from 75 Mbps to 290 Mbps with pulse rise and fall times of 400 ps. The pulse shapes of the laser diode and the response from the APD/preamplifier module were also measured.

  19. Resonant activation in bistable semiconductor lasers

    SciTech Connect

    Lepri, Stefano; Giacomelli, Giovanni

    2007-08-15

    We theoretically investigate the possibility of observing resonant activation in the hopping dynamics of two-mode semiconductor lasers. We present a series of simulations of a rate-equation model under random and periodic modulation of the bias current. In both cases, for an optimal choice of the modulation time scale, the hopping times between the stable lasing modes attain a minimum. The simulation data are understood by means of an effective one-dimensional Langevin equation with multiplicative fluctuations. Our conclusions apply to both edge-emitting and vertical cavity lasers, thus opening the way to several experimental tests in such optical systems.

  20. Semiconductor laser with the subhertz linewidth

    NASA Astrophysics Data System (ADS)

    Matveev, A. N.; Kolachevsky, N. N.; Alnis, J.; Hänsch, T. W.

    2008-10-01

    A semiconductor laser emitting at 972 nm is stabilised with respect to a vibrationally and thermally compensated reference Fabry—Perot resonator with the vertical axis. The supporting points lie in the horizontal symmetry plane of the resonator, the influence of vibrations in the vertical direction being substantially suppressed in this case. This configuration provides a low sensitivity of the laser emission frequency to vertical accelerations of the reference resonator. To reduce the influence of temperature fluctuations, the resonator is made of an ULE (ultra-low-expansion) glass and is kept at temperature at which the expansion coefficient of this glass is close to zero. The laser linewidth is smaller than 0.5 Hz and the frequency drift is ≈0.1 Hz s-1. The minimum of the Allan deviation achieved for 3 s is 2×10-15. The laser was used to record the spectra of the 1S—2S transition in atomic hydrogen.

  1. Semiconductor lasers for space beacons and communications

    NASA Astrophysics Data System (ADS)

    Kung, H.; Worland, D. P.; Nguyen, H.; Streifer, W.; Scifres, D. R.

    1989-06-01

    Semiconductor lasers have been packaged and qualified for various applications in space. In this paper two subsystems are discussed, both of which will be launched shortly. The first subsystem employs a partially coherent semiconductor laser array coupled to an optical fiber, and monitored by a photo-diode.This package is used in a highly reliable, moderate data rate, moderate length communications link. The fiber coupled output power is 28 mW and the package has been fully space qualified. That is, it is free of organics, hermetically sealed, and has been subjected to die shear, acceleration, thermal cycling, and other tests. The laser longevity exceeds 10 years of continuous operation. The second subsystem consists of 27 fiber coupled space qualified packaged lasers of the same type as above, but designed to operate at 200 mW power output from the fiber. Twenty-seven fibers are bundled to produce a source with a total power emission in excess of 5 watts cw. The subsystem is part of a beacon, which will be used very shortly in a polar satellite experiment. The lasers employed in the two subsystems described above are only partially coherent and therefore are insufficiently bright to operate in a long distance, high data rate link, except with a prohibitively large lens.

  2. On the nonlinear theory of Fabry-Perot semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Noppe, Michael G.

    2016-05-01

    Fundamentals of the nonlinear theory of Fabry-Perot semiconductor lasers have been developed, an integral part of which is natural linewidth theory. The formula for gain depending on the energy flux specifies the basic nonlinear effect in a laser. Necessary conditions for stimulated emission of the first and second kind are presented. Maxwell’s equations in the gain medium are applied to obtain equations for energy flux and for the description of non-linear phase effect. Based on the nonlinear theory, a number of experiments have been simulated; it indicates that the nonlinear theory is a new paradigm in laser theory. The nonlinear theory has provided recommendations for the development of lasers with improved properties, such as lasers with increased power and lasers with reduced natural linewidth.

  3. Information-theoretic secure key distribution based on common random-signal induced synchronization in unidirectionally-coupled cascades of semiconductor lasers.

    PubMed

    Koizumi, Hayato; Morikatsu, Shinichiro; Aida, Hiroki; Nozawa, Takahiro; Kakesu, Izumi; Uchida, Atsushi; Yoshimura, Kazuyuki; Muramatsu, Jun; Davis, Peter

    2013-07-29

    It has been proposed that a secure key distribution scheme using correlated random bit sequences can be implemented using common random-signal induced synchronization of semiconductor laser systems. In this scheme it is necessary to use laser systems consisting of multiple cascaded lasers to be secure against a powerful eavesdropper. In this paper, we report the results of an experimental study that demonstrate that the common random-signal induced synchronization is possible in cascaded semiconductor laser systems. We also show that the correlated random bit sequences generated in the synchronized cascaded laser systems can be used to create an information-theoretically secure key between two legitimate users.

  4. Use of a semiconductor diode laser in laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Sakr, Ghazi; Watson, Graham M.; Lawrence, William

    1996-05-01

    The gold standard surgical treatment of benign prostatic hyperplasia (BPH) is transurethral resection of the prostate (TURP). Over the past few years, TURP has been challenged by laser prostatectomy, a technique that offered many advantages including minimal bleeding, short hospital stay, no fluid absorption, rapid learning curve and better change to preserve antegrade ejaculation. Laser prostatectomy can be done by vaporizing or coagulating prostatic tissue and more recently by using a combination of both: The hybrid technique Nd:YAG lasers have been used, (coupled with contact tips or with side firing or even bare fibers) to either coagulate or vaporize prostatic tissue. Recently semiconductor diode lasers have become available and offer certain advantages. They are compact portable units with no need for water cooling, yet they have sufficient power for tissue vaporization. Diomed (Cambridge, U.K.), produces a 60 W gallium aluminum arsenide semiconductor diode laser emitting at 810 nm. We report the first clinical experience using a semiconductor diode laser for prostates using a combination of contact tip and sidefiring.

  5. Electrically pumped edge-emitting photonic bandgap semiconductor laser

    DOEpatents

    Lin, Shawn-Yu; Zubrzycki, Walter J.

    2004-01-06

    A highly efficient, electrically pumped edge-emitting semiconductor laser based on a one- or two-dimensional photonic bandgap (PBG) structure is described. The laser optical cavity is formed using a pair of PBG mirrors operating in the photonic band gap regime. Transverse confinement is achieved by surrounding an active semiconductor layer of high refractive index with lower-index cladding layers. The cladding layers can be electrically insulating in the passive PBG mirror and waveguide regions with a small conducting aperture for efficient channeling of the injection pump current into the active region. The active layer can comprise a quantum well structure. The quantum well structure can be relaxed in the passive regions to provide efficient extraction of laser light from the active region.

  6. Semiconductor disk laser pumped Cr2+:Znse lasers.

    PubMed

    Hempler, Nils; Hopkins, John-Mark; Rösener, Benno; Rattunde, Marcel; Wagner, Joachim; Fedorov, Vladimir V; Moskalev, Igor S; Mirov, Sergey B; Burns, David

    2009-09-28

    A new flexible pump source, the optically-pumped semiconductor disk laser (SDL), for the Cr(2+):ZnSe laser is reported. The SDL provides up to 6W output power at a free running central wavelength of 1.98 microm. The Cr(2+):ZnSe laser operated at an output power of 1.8W and a slope efficiency of approximately 50% with respect to absorbed pump power whilst maintaining a low output intensity noise figure of <0.14% RMS. The system required no optical isolation even under the situation of significant optical feedback.

  7. Approaches toward a blue semiconductor laser

    NASA Technical Reports Server (NTRS)

    Ladany, I.

    1989-01-01

    Possible approaches for obtaining semiconductor diode laser action in the blue region of the spectrum are surveyed. A discussion of diode lasers is included along with a review of the current status of visible emitters, presently limited to 670 nm. Methods are discussed for shifting laser emission toward shorter wavelengths, including the use of II-IV materials, the increase in the bandgap of III-V materials by addition of nitrogen, and changing the bandstructure from indirect to direct by incorporating interstitial atoms or by constructing superlattices. Non-pn-junction injection methods are surveyed, including avalanche breakdown, Langmuir-Blodgett diodes, heterostructures, carrier accumulation, and Berglund diodes. Prospects of inventing new multinary semiconducting materials are discussed, and a number of novel materials described in the literature are tabulated. New approaches available through the development of quantum wells and superlattices are described, including resonant tunneling and the synthesis of arbitrary bandgap materials through multiple quantum wells.

  8. Timing and amplitude jitter in a gain-switched multimode semiconductor laser

    NASA Astrophysics Data System (ADS)

    Wada, Kenji; Kitagawa, Naoaki; Matsukura, Satoru; Matsuyama, Tetsuya; Horinaka, Hiromichi

    2016-04-01

    The differences in timing jitter between a gain-switched single-mode semiconductor laser and a gain-switched multimode semiconductor laser are examined using rate equations that include Langevin noise. The timing jitter in a gain-switched multimode semiconductor laser is found to be effectively suppressed by a decrease in the coherence time of the amplified spontaneous emission (ASE) based on a broad bandwidth of multimode oscillation. Instead, fluctuations in the ASE cause amplitude jitter in the pulse components of the respective modes. A pulse train of gain-switched pulses from a multimode semiconductor laser with timing jitter is equivalently simulated by assuming a high spontaneous emission factor and a short coherence time of the ASE in the single-mode semiconductor laser rate equations.

  9. Optical-cell model based on the lasing competition of mode structures with different Q-factors in high-power semiconductor lasers

    SciTech Connect

    Podoskin, A. A. Shashkin, I. S.; Slipchenko, S. O.; Pikhtin, N. A.; Tarasov, I. S.

    2015-08-15

    A model describing the operation of a completely optical cell, based on the competition of lasing of Fabry-Perot cavity modes and the high-Q closed mode in high-power semiconductor lasers is proposed. Based on rate equations, the conditions of lasing switching between Fabry-Perot modes for ground and excited lasing levels and the closed mode are considered in the case of increasing internal optical loss under conditions of high current pump levels. The optical-cell operation conditions in the mode of a high-power laser radiation switch (reversible mode-structure switching) and in the mode of a memory cell with bistable irreversible lasing switching between mode structures with various Q-factors are considered.

  10. Self-collimated unstable resonator semiconductor laser

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1993-01-01

    Self-collimation of the output is achieved in an unstable resonator semiconductor laser by providing a large concave mirror M sub 1 and a small convex mirror M sub 2 on opposite surfaces of a semiconductor body of a material having an effective index of refraction denoted by n, where the respective mirror radii R sub 1, R sub 2 and beam radii r sub 1, r sub 2 are chosen to satisfy a condition (R sub 2)/(1 + r sub 1) = (n - 1)/n, with a value of geometric magnification 1 less than or equal to M less than or equal to (n + 1)/(n - 1) where r sub 1 and r sub 2 are the radii of counterpropagating beams at respective mirrors of radii R sub 1 and R sub 2.

  11. Semiconductor Lasers Containing Quantum Wells in Junctions

    NASA Technical Reports Server (NTRS)

    Yang, Rui Q.; Qiu, Yueming

    2004-01-01

    In a recent improvement upon In(x)Ga(1-x)As/InP semiconductor lasers of the bipolar cascade type, quantum wells are added to Esaki tunnel junctions, which are standard parts of such lasers. The energy depths and the geometric locations and thicknesses of the wells are tailored to exploit quantum tunneling such that, as described below, electrical resistances of junctions and concentrations of dopants can be reduced while laser performances can be improved. In(x)Ga(1-x)As/InP bipolar cascade lasers have been investigated as sources of near-infrared radiation (specifically, at wavelengths of about 980 and 1,550 nm) for photonic communication systems. The Esaki tunnel junctions in these lasers have been used to connect adjacent cascade stages and to enable transport of charge carriers between them. Typically, large concentrations of both n (electron-donor) and p (electron-acceptor) dopants have been necessary to impart low electrical resistances to Esaki tunnel junctions. Unfortunately, high doping contributes free-carrier absorption, thereby contributing to optical loss and thereby, further, degrading laser performance. In accordance with the present innovation, quantum wells are incorporated into the Esaki tunnel junctions so that the effective heights of barriers to quantum tunneling are reduced (see figure).

  12. Visible-wavelength semiconductor lasers and arrays

    DOEpatents

    Schneider, R.P. Jr.; Crawford, M.H.

    1996-09-17

    The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1{lambda}) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%. 5 figs.

  13. Thermal runaway in semiconductor laser windows.

    PubMed

    Johnson, R L; O'Keefe, J D

    1972-12-01

    A small perturbation model is used to obtain analytical expressions for the critical or runaway power density for laser windows constructed of semiconductor materials. These equations are used to compute the critical power density for several realistic window installations taking account of the finite value of realizable convection cooling coefficients. Computations were prepared for silicon transmitting 4 .0-micro. radiation and for germanium at 10.6 micro. In this way it is shown that power densities are principally limited by the effectiveness of cooling from the face of the window, that is, the surface perpendicular to the laser beam. Since convection cooling coefficients are small the transmission of high power densities through semiconductor windows is therefore contingent upon finding more effective means to cool the window from the face. Finally, a simplified calculation was made in an attempt to account for nonuniformity of the incident laser beam. a given window, but not severely. The results show the onuniformity reduces the runaway power for a given window, but not severely.

  14. Power semiconductor laser diode arrays characterization

    NASA Astrophysics Data System (ADS)

    Zeni, Luigi; Campopiano, Stefania; Cutolo, Antonello; D'Angelo, Giuseppe

    2003-09-01

    Nowadays, power semiconductor laser diode arrays are becoming a widespread source for a large variety of industrial applications. In particular, the availability of low-cost high-power laser diode arrays makes their use possible in the industrial context for material cutting, welding, diagnostics and processing. In the above applications, the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. In this paper, we present two different approaches useful for the characterization of the beam quality in laser diode arrays. The first one, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The second one is aimed at the measurement of a global quality factor of the array itself; to this end, the empirical extension of the M2 concept to composite beams is presented along with some experimental results. As the first technique is especially intended for the non-destructive detection of design problems in the array itself and in the bias circuitry, the second one represents a powerful tool for the rapid on-line diagnostics of the laser beam during its use.

  15. Subwavelength Nanopatch Cavities for Semiconductor Plasmon Lasers

    NASA Astrophysics Data System (ADS)

    Manolatou, Christina; Rana, Farhan

    2008-05-01

    We propose and analyze a family of nanoscale cavities for electrically-pumped surface-emitting semiconductor lasers that use surface plasmons to provide optical mode confinement in cavities which have dimensions in the 100-300 nm range. The proposed laser cavities are in many ways nanoscale optical versions of micropatch antennas that are commonly used at microwave/RF frequencies. Surface plasmons are not only used for mode confinement but also for output beam shaping to realize single-lobe far-field radiation patterns with narrow beam waists from subwavelength size cavities. We identify the cavity modes with the largest quality factors and modal gain, and show that in the near-IR wavelength range (1.0-1.6 microns) cavity losses (including surface plasmon losses) can be compensated by the strong mode confinement in the gain region provided by the surface plasmons themselves and the required material threshold gain values can be smaller than 700 1/cm.

  16. Self-mode-locking semiconductor disk laser.

    PubMed

    Gaafar, Mahmoud; Richter, Philipp; Keskin, Hakan; Möller, Christoph; Wichmann, Matthias; Stolz, Wolfgang; Rahimi-Iman, Arash; Koch, Martin

    2014-11-17

    The development of mode-locked semiconductor disk lasers received striking attention in the last 14 years and there is still a vast potential of such pulsed lasers to be explored and exploited. While for more than one decade pulsed operation was strongly linked to the employment of a saturable absorber, self-mode-locking emerged recently as an effective and novel technique in this field - giving prospect to a reduced complexity and improved cost-efficiency of such lasers. In this work, we highlight recent achievements regarding self-mode-locked semiconductor devices. It is worth to note, that although nonlinear effects in the active medium are expected to give rise to self-mode-locking, this has to be investigated with care in future experiments. However, there is a controversy whether results presented with respect to self-mode-locking truly show mode-locking. Such concerns are addressed in this work and we provide a clear evidence of mode-locking in a saturable-absorber-free device. By using a BBO crystal outside the cavity, green light originating from second-harmonic generation using the out-coupled laser beam is demonstrated. In addition, long-time-span pulse trains as well as radiofrequency-spectra measurements are presented for our sub-ps pulses at 500 MHz repetition rate which indicate the stable pulse operation of our device. Furthermore, a long-time-span autocorrelation trace is introduced which clearly shows absence of a pedestal or double pulses. Eventually, a beam-profile measurement reveals the excellent beam quality of our device with an M-square factor of less than 1.1 for both axes, showing that self-mode-locking can be achieved for the fundamental transverse mode.

  17. Modulation Effects in Multi-Section Semiconductor Lasers (Postprint)

    DTIC Science & Technology

    2013-01-01

    resonant modulation of semiconductor lasers beyond relaxation oscillation frequency,” Appl. Phys. Lett., 63, 1459–1461 (1993). [26] J. Helms and K. Petermann ...5, 4–6 (1993). [28] K. Petermann , “External optical feedback phenomena in semiconductor lasers,” IEEE J. Sel. Top. Quantum Elec- tron., 1, 480–489

  18. Laser cooling of a semiconductor by 40 kelvin.

    PubMed

    Zhang, Jun; Li, Dehui; Chen, Renjie; Xiong, Qihua

    2013-01-24

    absorption. Our findings suggest that, alternatively, group-II-VI semiconductors with strong exciton-LOP coupling could be harnessed to achieve laser cooling and open the way to optical refrigeration based on semiconductors.

  19. Electron circuits: Semiconductor laser multiple use installation

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Fan, J.; Weng, D.

    1983-04-01

    A light source for a multiple use installation using a same matter junction or different matter junction GaAlAs/GaAs semiconductor laser, which has the advantages of high interference resistance, long transmission distance (tens to hundreds of meters), good security, and low power consumption; in addition, the controller of the light source has multiple usages of alarming, switching and counting is presented. The multiple use installation can be used in control of breaking warps and counting on roving waste machines, warping machines and silk weaving machines in the textile industry; long distance speed measurement, alarming and counting in machinery, electricity and chemical industries; and alarming and control of water levels in reservoirs, rivers and water towers, as well as blockade alarming and control of important divisions. This multiple use installation is composed of two parts a laser emitter and a receiving device. The former component is used to produce the laser; after the receiver receives the laser, the installation completes operations of alarming, switching and counting.

  20. Phase-Locked Semiconductor Lasers With Separate Contacts

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Yariv, Amnon; Margalit, Shlomo

    1988-01-01

    Individual current feeds enable better uniformity and flexible control. Separate contacts for lasers in array enable control of output radiation pattern and compensation of manufacturing nonuniformities among lasers. Concept of separate current control described for two-laser array in "Semiconductor Laser Phased Array" (NPO-15963).

  1. Modes in light wave propagating in semiconductor laser

    NASA Technical Reports Server (NTRS)

    Manko, Margarita A.

    1994-01-01

    The study of semiconductor laser based on an analogy of the Schrodinger equation and an equation describing light wave propagation in nonhomogeneous medium is developed. The active region of semiconductor laser is considered as optical waveguide confining the electromagnetic field in the cross-section (x,y) and allowing waveguide propagation along the laser resonator (z). The mode structure is investigated taking into account the transversal and what is the important part of the suggested consideration longitudinal nonhomogeneity of the optical waveguide. It is shown that the Gaussian modes in the case correspond to spatial squeezing and correlation. Spatially squeezed two-mode structure of nonhomogeneous optical waveguide is given explicitly. Distribution of light among the laser discrete modes is presented. Properties of the spatially squeezed two-mode field are described. The analog of Franck-Condon principle for finding the maxima of the distribution function and the analog of Ramsauer effect for control of spatial distribution of laser emission are discussed.

  2. Multi-spectral imaging with mid-infrared semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Wang, Yang; Le, Han Q.

    2006-01-01

    Multi-spectral laser imaging can be a useful technology for target discrimination, classification, and identification based on object spectral signatures. The mid-IR region (~3-14 μm) is particularly rich of molecular spectroscopic fingerprints, but the technology has been under utilized. Compact, potentially inexpensive semiconductor lasers may allow more cost-effective applications. This paper describes a development of semiconductor-laser-based multi-spectral imaging for both near-IR and mid-IR, and demonstrates the potential of this technology. The near-IR study employed 7 wavelengths from 0.635-1.55 μm, and used for system engineering evaluation as well as for studying the fundamental aspects of multi-spectral laser imaging. These include issues of wavelength-dependence scattering as a function of incident and receiving angle and the polarization effects. Stokes vector imaging and degree-of-linear-polarization were shown to reveal significant information to characterize the targets. The mid-IR study employed 4 wavelengths from 3.3-9.6 μm, and was applied to diverse targets that consist of natural and man-made materials and household objects. It was shown capable to resolve and distinguish small spectral differences among various targets, thanks to the laser radiometric and spectral accuracy. Colorless objects in the visible were shown with "colorful" signatures in the mid-IR. An essential feature of the study is an advanced system architecture that employs wavelength-division-multiplexed laser beams for high spectral fidelity and resolution. In addition, unlike conventional one-transmitter and one receiver design, the system is based on a scalable CDMA network concept with multiple transmitters and receivers to allow efficient information acquisition. The results suggest that multi-spectral laser imaging in general can be a unique and powerful technology for wide ranging applications.

  3. Semiconductor single crystal external ring resonator cavity laser and gyroscope

    SciTech Connect

    Spitzer, M.P.

    1993-08-31

    A ring laser is described comprising: a semiconductor single crystal external ring resonator cavity having a plurality of reflecting surfaces defined by the planes of the crystal and establishing a closed optical path; and a discrete laser medium disposed in said semiconductor single crystal external ring resonator cavity for generating coherent light in said cavity, wherein said resonator cavity is decoupled from the laser medium.

  4. Laser micromachining of semiconductors for photonics applications

    NASA Astrophysics Data System (ADS)

    Nantel, Marc; Yashkir, Yuri; Lee, Seong K.; Mugford, Chas; Hockley, Bernard S.

    2001-10-01

    For decades, precisely machining silicon has been critical for the success of the semiconductor industry. This has traditionally been done through wet chemical etching, but in the pursuit of integrating photonics devices on a single chip, other techniques are worth exploring. This quest opens up interest in finding a non-wet, non-contact, arbitrary-shape milling technique for silicon. In this paper, we present our latest work in the laser micromachining of silicon. A kilohertz-repetition-rate diode-pumped Nd:YLF laser (in infrared, green or ultraviolet modes) is focused on the surface of silicon wafers in a chlorine atmosphere for an enhanced magnitude and control of the etching rate. In the chlorine atmosphere, much less debris is deposited on the surface around the cut, sub-damage threshold machining is achieved for a better control of the etching depth, and etching rates ranging from 20-300,000 micron-cube/s have been measured. In particular, the use of an infrared laser beam is singled out, along with the advantages that it holds. Results of simulations highlight the particular characteristics of the various wavelength chosen for the machining.

  5. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum

    PubMed Central

    Seghilani, Mohamed S.; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-01-01

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here “orbital birefringence”, based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create “orbital gain dichroism” allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications. PMID:27917885

  6. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum

    NASA Astrophysics Data System (ADS)

    Seghilani, Mohamed S.; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-12-01

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here “orbital birefringence”, based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create “orbital gain dichroism” allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications.

  7. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum.

    PubMed

    Seghilani, Mohamed S; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-12-05

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here "orbital birefringence", based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create "orbital gain dichroism" allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications.

  8. Photon number squeezed states in semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Yamamoto, Yoshihisa; Machida, Susumu; Richardson, Wayne H.

    1992-01-01

    Electromagnetic fields, with the noise on one quadrature component reduced to below the quantum mechanical zero-point fluctuation level and the noise on the other quadrature component enhanced to above it, are currently of great interest in quantum optics because of their potential applications to various precision measurements. Such squeezed states of light are usually produced by imposing nonlinear unitary evolution on coherent (or vacuum) states. On the other hand, squeezed states with reduced photon number noise and enhanced phase noise are generated directly by a constant current-driven semiconductor laser. This is the simplest scheme for the generation of nonclassical light, and so far it has yielded the largest quantum noise reduction. The mutual coupling between a lasing junction and an external electrical circuit provides opportunities for exploring the macroscopic and microscopic quantum effects in open systems.

  9. Mode beating and heterodyning of monolithically integrated semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Liu, Chiyu

    Monolithically integrated semiconductor ring lasers (SRLs) are attractive optical sources for optoelectronic integrated circuits (OEICs) because they do not require any feedback elements, do not have parts exposed to external ambient, and can operate in a traveling-wave mode. They are promising candidates for wavelength filtering, unidirectional traveling-wave operation, and multiplexing/demultiplexing applications. Ring lasers can also be used as ultrashort pulse generators using various mode-locking schemes and as active gyro components. However, the SRL is a very complicated dynamic system, which requires more investigations to understand the performance regarding details of the design and fabrication. As a part of NASA-supported project "Monolithically Integrated Semiconductor Ring Laser Gyro for Space Applications", this dissertation research was focused on design and characterization of a novel monolithically integrated rotation sensor based on two large-size independent SRLs. Numerical modeling based on the beam propagation method (BPM) was used to design the fabrication parameters for the single-mode ridge-waveguide ring cavity and directional coupler waveguides. The mode internal coupling in single lateral-mode laser diodes with InGaAs/GaAs material system was investigated by optical experiments and numerical modeling. To gain the understanding of the SRL performance, optical and electrical characterization was performed on fabricated SRLs. Particular emphasis was placed on the study of optical and radio frequency (RF) beating spectra of longitudinal modes of ring lasers. RF measurements provide high accuracy in the diagnosis of laser oscillation parameters by purely electronic means, particularly in the measurement of the group index and its dependence on current and temperature. Theoretical analysis based on the effective index method provides good agreement between the experimental data and numerical calculations. Finally, optical heterodyning spectra

  10. Suppression of phase and supermode noise in a harmonic mode-locked erbium-doped fiber laser with a semiconductor-optical-amplifier-based high-pass filter.

    PubMed

    Lin, Gong-Ru; Wu, Ming-Chung; Chang, Yung-Cheng

    2005-07-15

    By operating an intracavity semiconductor-optical-amplifier- (SOA-) based high-pass filter at the nearly transparent current condition, the supermode noise (SMN), the relaxation oscillation, and the single-sideband (SSB) phase noise can be simultaneously suppressed in an actively mode-locked erbium-doped fiber laser (EDFL). The SOA at the nearly transparent condition enhances the SMN suppression ratio of the EDFL from 32 to 76 dB at the cost of the phase noise degrading from -114 to -104.2 dBc/Hz and broadening the pulse width from 36 to 61 ps. With an optical bandpass filter, the SSB phase noise and the SMN suppression ratio can be further improved to -110 dBc/Hz and 81 dB, respectively. The EDFL pulse can be further shortened to 3.1 ps with a time-bandwidth product of 0.63 after compression.

  11. Thienoacene-based organic semiconductors.

    PubMed

    Takimiya, Kazuo; Shinamura, Shoji; Osaka, Itaru; Miyazaki, Eigo

    2011-10-11

    Thienoacenes consist of fused thiophene rings in a ladder-type molecular structure and have been intensively studied as potential organic semiconductors for organic field-effect transistors (OFETs) in the last decade. They are reviewed here. Despite their simple and similar molecular structures, the hitherto reported properties of thienoacene-based OFETs are rather diverse. This Review focuses on four classes of thienoacenes, which are classified in terms of their chemical structures, and elucidates the molecular electronic structure of each class. The packing structures of thienoacenes and the thus-estimated solid-state electronic structures are correlated to their carrier transport properties in OFET devices. With this perspective of the molecular structures of thienoacenes and their carrier transport properties in OFET devices, the structure-property relationships in thienoacene-based organic semiconductors are discussed. The discussion provides insight into new molecular design strategies for the development of superior organic semiconductors.

  12. Monolayer semiconductor nanocavity lasers with ultralow thresholds.

    PubMed

    Wu, Sanfeng; Buckley, Sonia; Schaibley, John R; Feng, Liefeng; Yan, Jiaqiang; Mandrus, David G; Hatami, Fariba; Yao, Wang; Vučković, Jelena; Majumdar, Arka; Xu, Xiaodong

    2015-04-02

    Engineering the electromagnetic environment of a nanometre-scale light emitter by use of a photonic cavity can significantly enhance its spontaneous emission rate, through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter, providing a low-threshold laser system with small footprint, low power consumption and ultrafast modulation. An ultralow-threshold nanoscale laser has been successfully developed by embedding quantum dots into a photonic crystal cavity (PCC). However, several challenges impede the practical application of this architecture, including the random positions and compositional fluctuations of the dots, extreme difficulty in current injection, and lack of compatibility with electronic circuits. Here we report a new lasing strategy: an atomically thin crystalline semiconductor--that is, a tungsten diselenide monolayer--is non-destructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PCC. A continuous-wave nanolaser operating in the visible regime is thereby achieved with an optical pumping threshold as low as 27 nanowatts at 130 kelvin, similar to the value achieved in quantum-dot PCC lasers. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within one nanometre of the PCC surface. The surface-gain geometry gives unprecedented accessibility and hence the ability to tailor gain properties via external controls such as electrostatic gating and current injection, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.

  13. Gain Coupling of Class A Semiconductor Lasers (Postprint)

    DTIC Science & Technology

    2010-09-01

    AFRL-RY-WP-TP-2010-1250 GAIN COUPLING OF CLASS A SEMICONDUCTOR LASERS (POSTPRINT) Chris Hessenius, Mahmoud Fallahi, and Jerome Moloney...PROGRAM ELEMENT NUMBER 62204F 6. AUTHOR(S) Chris Hessenius, Mahmoud Fallahi, and Jerome Moloney (University of Arizona) Nathan Terry and Robert...98) Prescribed by ANSI Std. Z39-18 Gain coupling of class A semiconductor lasers Chris Hessenius,1,* Nathan Terry,2 Mahmoud Fallahi,1 Jerome

  14. Picosecond Semiconductor Lasers For Characterizing High-Speed Image Shutters

    NASA Astrophysics Data System (ADS)

    Pagano, T. S.; Janson, F. J.; Yates, G. J.; Jaramillo, S. A.

    1986-01-01

    A portable system that utilizes solid state electronic timing circuits and a pulsed semiconductor laser for characterizing the optical gate sequence of high-speed image shutters, including microchannel-plate intensifier tubes (MCPTs), and silicon-intensified target vidicons (SITVs), is described and compared to earlier methods of characterization. Gate sequences obtained using the system and streak camera data of the semiconductor laser pulse are presented, with a brief discussion of the electronic delay timing and avalanche circuits used in the system.

  15. Frequency offset locking of AlGaAs semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Kuboki, Katsuhiko; Ohtsu, Motoichi

    1987-04-01

    Frequency offset locking is proposed as a technique for tracking and sweeping of a semiconductor laser frequency to improve temporal coherence in semiconductor lasers. Experiments were carried out in which a frequency stabilized laser (of residual frequency fluctuation value of 140 Hz at the integration time between 100 ms and 100 s) was used as a master laser, using a digital phase comparator of a large dynamic range (2 pi x 10 to the 11th rad) in the feedback loop to reduce the phase fluctuations of the beat signal between the master laser and the slave laser. As a result, residual frequency fluctuations of the beat signal were as low as 11 Hz at the integration time of 100 s (i.e., the residual frequency fluctuations of the slave laser were almost equal to those of the master laser).

  16. EDITORIAL: Frontiers in semiconductor-based devices Frontiers in semiconductor-based devices

    NASA Astrophysics Data System (ADS)

    Krishna, Sanjay; Phillips, Jamie; Ghosh, Siddhartha; Ma, Jack; Sabarinanthan, Jayshri; Stiff-Roberts, Adrienne; Xu, Jian; Zhou, Weidong

    2009-12-01

    This special cluster of Journal of Physics D: Applied Physics reports proceedings from the Frontiers in Semiconductor-Based Devices Symposium, held in honor of the 60th birthday of Professor Pallab Bhattacharya by his former doctoral students. The symposium took place at the University of Michigan, Ann Arbor on 6-7 December 2009. Pallab Bhattacharya has served on the faculty of the Electrical Engineering and Computer Science Department at the University of Michigan, Ann Arbor for 25 years. During this time, he has made pioneering contributions to semiconductor epitaxy, characterization of strained heterostructures, self-organized quantum dots, quantum-dot optoelectronic devices, and integrated optoelectronics. Professor Bhattacharya has been recognized for his accomplishments by membership of the National Academy of Engineering, by chaired professorships (Charles M Vest Distinguished University Professor and James R Mellor Professor of Engineering), and by selection as a Fellow of the IEEE, among numerous other honors and awards. Professor Bhattacharya has also made remarkable contributions in education, including authorship of the textbook Semiconductor Optoelectronic Devices (Prentice Hall, 2nd edition) and the production of 60 PhD students (and counting). In fact, this development of critical human resources is one of the biggest impacts of Professor Bhattacharya's career. His guidance and dedication have shaped the varied professional paths of his students, many of whom currently enjoy successful careers in academia, industry, and government around the world. This special cluster acknowledges the importance of Professor Bhattacharya's influence as all of the contributions are from his former doctoral students. The symposium reflects the significant impact of Professor Bhattacharya's research in that the topics span diverse, critical research areas, including: semiconductor lasers and modulators, nanoscale quantum structure-based devices, flexible CMOS-based

  17. Monolayer semiconductor nanocavity lasers with ultralow thresholds

    SciTech Connect

    Wu, Sanfeng; Buckley, Sonia; Schaibley, John R.; Feng, Liefeng; Yan, Jiaqiang; Mandrus, David G.; Hatami, Fariba; Yao, Wang; Vučković, Jelena; Majumdar, Arka; Xu, Xiaodong

    2015-03-16

    Engineering the electromagnetic environment of a nanoscale light emitter by a photonic cavity can significantly enhance its spontaneous emission rate through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter1–5, providing the ultimate low-threshold laser system with small footprint, low power consumption and ultrafast modulation. A state-of-the-art ultra-low threshold nanolaser has been successfully developed though embedding quantum dots into photonic crystal cavity (PhCC)6–8. However, several core challenges impede the practical applications of this architecture, including the random positions and compositional fluctuations of the dots7, extreme difficulty in current injection8, and lack of compatibility with electronic circuits7,8. Here, we report a new strategy to lase, where atomically thin crystalline semiconductor, i.e., a tungsten-diselenide (WSe2) monolayer, is nondestructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PhCC. A new type of continuous-wave nanolaser operating in the visible regime is achieved with an optical pumping threshold as low as 27 nW at 130 K, similar to the value achieved in quantum dot PhCC lasers7. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within 1 nm of the PhCC surface. The surface-gain geometry allows unprecedented accessibilities to multi-functionalize the gain, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.

  18. Monolayer semiconductor nanocavity lasers with ultralow thresholds

    DOE PAGES

    Wu, Sanfeng; Buckley, Sonia; Schaibley, John R.; ...

    2015-03-16

    Engineering the electromagnetic environment of a nanoscale light emitter by a photonic cavity can significantly enhance its spontaneous emission rate through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter1–5, providing the ultimate low-threshold laser system with small footprint, low power consumption and ultrafast modulation. A state-of-the-art ultra-low threshold nanolaser has been successfully developed though embedding quantum dots into photonic crystal cavity (PhCC)6–8. However, several core challenges impede the practical applications of this architecture, including the random positions and compositional fluctuations of the dots7, extreme difficulty in current injection8, and lackmore » of compatibility with electronic circuits7,8. Here, we report a new strategy to lase, where atomically thin crystalline semiconductor, i.e., a tungsten-diselenide (WSe2) monolayer, is nondestructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PhCC. A new type of continuous-wave nanolaser operating in the visible regime is achieved with an optical pumping threshold as low as 27 nW at 130 K, similar to the value achieved in quantum dot PhCC lasers7. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within 1 nm of the PhCC surface. The surface-gain geometry allows unprecedented accessibilities to multi-functionalize the gain, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.« less

  19. Hybrid organic semiconductor lasers for bio-molecular sensing.

    PubMed

    Haughey, Anne-Marie; Foucher, Caroline; Guilhabert, Benoit; Kanibolotsky, Alexander L; Skabara, Peter J; Burley, Glenn; Dawson, Martin D; Laurand, Nicolas

    2014-01-01

    Bio-functionalised luminescent organic semiconductors are attractive for biophotonics because they can act as efficient laser materials while simultaneously interacting with molecules. In this paper, we present and discuss a laser biosensor platform that utilises a gain layer made of such an organic semiconductor material. The simple structure of the sensor and its operation principle are described. Nanolayer detection is shown experimentally and analysed theoretically in order to assess the potential and the limits of the biosensor. The advantage conferred by the organic semiconductor is explained, and comparisons to laser sensors using alternative dye-doped materials are made. Specific biomolecular sensing is demonstrated, and routes to functionalisation with nucleic acid probes, and future developments opened up by this achievement, are highlighted. Finally, attractive formats for sensing applications are mentioned, as well as colloidal quantum dots, which in the future could be used in conjunction with organic semiconductors.

  20. High-power semiconductor laser array packaged on microchannel cooler using gold-tin soldering technology

    NASA Astrophysics Data System (ADS)

    Wang, Jingwei; Kang, Lijun; Zhang, Pu; Nie, Zhiqiang; Li, Xiaoning; Xiong, Lingling; Liu, Xingsheng

    2012-03-01

    High power semiconductor laser arrays have found increased applications in many fields. In this work, a hard soldering microchannel cooler (HSMCC) technology was developed for packaging high power diode laser array. Numerical simulations of the thermal behavior characteristics of hard solder and indium solder MCC-packaged diode lasers were conducted and analyzed. Based on the simulated results, a series of high power HSMCC packaged diode laser arrays were fabricated and characterized. The test and statistical results indicated that under the same output power the HSMCC packaged laser bar has lower smile and high reliability in comparison with the conventional copper MCC packaged laser bar using indium soldering technology.

  1. Broadly tunable DBR-free semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Hackett, Shawn; Sheik-Bahae, Mansoor

    2016-03-01

    We report a DBR-free semiconductor disk lasers centered at 1160 nm with a tuning range of 78 nm, and ongoing effort on our DBR-free SDL centered at 1040 nm. Compared with conventional semiconductor disk lasers, DBR-free SDLs have a broader effective gain bandwidth. In CW operation, 2.5 W output power at 1160 nm and 6 W at 1055 nm were collected from the two lasers without thermal-rollover. Intracavity loss mitigation, currently underway, should improve power scaling and efficiency in these systems.

  2. FM characteristics and compact modules for coherent semiconductor lasers coupled to an external cavity

    SciTech Connect

    Shin, C.H.; Teshima, M.; Ohtsu, M. ); Imai, T.; Yoshida, J.; Nishide, K. )

    1990-03-01

    FM responses of a semiconductor laser optically coupled off-axis to a confocal Fabry--Perot cavity were measured. It is reported that this cavity acted as a frequency discriminator and as a phase comparator for slow and fast frequency fluctuations, respectively. The crossover between them was determined by a half linewidth of the cavity. Based on these investigations, we made two kinds of coherent semiconductor laser modules. External FP cavities were made by using an optical fiber and a hemispherical micro-lens, respectively. Linewidths of these lasers were less than 25 kHz.

  3. Direct solar pumping of semiconductor lasers: A feasibility study

    NASA Technical Reports Server (NTRS)

    Anderson, Neal G.

    1992-01-01

    This report describes results of NASA Grant NAG-1-1148, entitled Direct Solar Pumping of Semiconductor Lasers: A Feasibility Study. The goals of this study were to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space with directly focused sunlight and to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or storage battery electrically pumping a current injection laser. With external modulation, such lasers could perhaps be efficient sources for intersatellite communications. We proposed specifically to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation at low pump intensities. These tasks have been accomplished, as described in this report of our completed project. The report is organized as follows: Some general considerations relevant to the solar-pumped semiconductor laser problem are discussed in Section 2, and the types of structures chosen for specific investigation are described. The details of the laser model we developed for this work are then outlined in Section 3. In Section 4, results of our study are presented, including designs for optimum lattice-matched and strained-layer solar-pumped quantum-well lasers and threshold pumping estimates for these structures. It was hoped at the outset of this work that structures could be identified which could be expected to operate continuously at solar photoexcitation intensities of several thousand suns, and this indeed turned out to be the case as described in this section. Our project is

  4. Semiconductor laser multi-spectral sensing and imaging.

    PubMed

    Le, Han Q; Wang, Yang

    2010-01-01

    Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

  5. Semiconductor Laser Multi-Spectral Sensing and Imaging

    PubMed Central

    Le, Han Q.; Wang, Yang

    2010-01-01

    Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers. PMID:22315555

  6. The 1.083 micron tunable CW semiconductor laser

    NASA Technical Reports Server (NTRS)

    Wang, C. S.; Chen, Jan-Shin; Lu, Ken-Gen; Ouyang, Keng

    1991-01-01

    A tunable CW laser is desired to produce light equivalent to the helium spectral line at 1.08 microns. This laser will serve as an optical pumping source for He-3 and He-4 atoms used in space magnetometers. This light source can be fabricated either as a semiconductor laser diode or a pumped solid state laser. Continuous output power of greater than 10 mW is desired. Semiconductor lasers can be thermally tuned, but must be capable of locking onto the helium resonance lines. Solid state lasers must have efficient pumping sources suitable for space configuration. Additional requirements are as follows: space magnetometer applications will include low mass (less than 0.5 kg), low power consumption (less than 0.75 W), and high stability/reliability for long missions (5-10 years).

  7. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    SciTech Connect

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V; Ladugin, M A; Marmalyuk, A A; Chamorovsky, A Yu; Yakubovich, S D

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  8. Monolithically integrated semiconductor ring lasers: Design, fabrication, and directional control

    NASA Astrophysics Data System (ADS)

    Cao, Hongjun

    Monolithic semiconductor ring lasers (SRLs) are attractive light sources for optoelectronic integrated circuits (OEICs) due to their convenience in monolithic integration: neither cleaved facets nor gratings are required for optical feedback. They are promising candidates for wavelength filtering, multiplexing-demultiplexing applications, electrical or all-optical switching, gating, and memories, and particularly, optical inertial rotation sensors or ring laser gyros. As the major part of a NASA-supported project "Monolithically integrated semiconductor ring laser gyro for space applications," this dissertation research was focused on design, fabrication, and directional control of monolithically integrated SRLs with relatively large size and sophisticated OEIC structures. The main potential application is the next-generation monolithic ring laser gyros. Specifically, monolithic SRLs with the longest reported cavity of 10.28 mm have been demonstrated. In device characterization, differential I-V analysis has been used for the first time in SRLs for purely electrical identification of lasing threshold and directional switching. Sophisticated device structures have been devised, including optically independent novel ring laser pairs, from which frequency beating between monolithically integrated SRLs was reported for the first time. In addition, no frequency lock-in was observed in the beating spectra, indicating an important progress for proposed gyro applications. Functional OEIC components including photodetectors, passive and active waveguides, and novel Joule heaters have been integrated on-chip along with the ring lasers. Mode competition, directional switching, bistability, and bidirectional and unidirectional operation in SRLs have been investigated. Directional control techniques with asymmetric mechanisms including spiral and S-section waveguides have been implemented. The S-section was investigated and analyzed in great detail for its suppression of

  9. Metal Organic-Chemical Vapor Deposition fabrication of semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Thomas, C.

    1980-08-01

    The metal organic chemical vapor deposition (MO-CVD) process was studied and implemented in detail. Single crystal GaAs, and Ga(x)Al(1-x)As films were grown on GaAs by depositing metal organic alkyl gallium compounds in the presence of an arsine mixture. The metal organic chemical vapor deposition process allowed formation of the semiconductor compound directly on the heated substrate in only one hot temperature zone. With MO-CVD, semiconductor films can be efficiently produced by a more economical, less complicated process which will lend itself more easily than past fabrication procedures, to high quantity, high quality reproduction techniques of semiconductor lasers. Clearly MO-CVD is of interest to the communication industry where semiconductor lasers are used extensively in fiber optic communication systems, and similarly to the solar energy business where GaAs substrates are used as photoelectric cells.

  10. Plastic lab-on-a-chip for fluorescence excitation with integrated organic semiconductor lasers.

    PubMed

    Vannahme, Christoph; Klinkhammer, Sönke; Lemmer, Uli; Mappes, Timo

    2011-04-25

    Laser light excitation of fluorescent markers offers highly sensitive and specific analysis for bio-medical or chemical analysis. To profit from these advantages for applications in the field or at the point-of-care, a plastic lab-on-a-chip with integrated organic semiconductor lasers is presented here. First order distributed feedback lasers based on the organic semiconductor tris(8-hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyril)-4H-pyrane (DCM), deep ultraviolet induced waveguides, and a nanostructured microfluidic channel are integrated into a poly(methyl methacrylate) (PMMA) substrate. A simple and parallel fabrication process is used comprising thermal imprint, DUV exposure, evaporation of the laser material, and sealing by thermal bonding. The excitation of two fluorescent marker model systems including labeled antibodies with light emitted by integrated lasers is demonstrated.

  11. Six-wave mixing theory of tilted-grating, broad-area semiconductor diode lasers with suppressed filamentation

    NASA Astrophysics Data System (ADS)

    Thompson, William Ellison, III

    Modern semiconductor diode lasers are appealing sources of laser radiation for many applications. However, an important disadvantage of semiconductor diode lasers as laser sources for the widest range of applications is that they are limited in output power. The output power of typical narrow-stripe semiconductor diode lasers is limited by thermal runaway effects that cause catastrophic facet damage to the device. To address this problem, researchers have developed broad-area diode lasers that can achieve increased output power by virtue of their larger emission area on the facet. In practice, however, the loss of lateral confinement that produces single-mode lasing in narrow-stripe semiconductor diode lasers leads to complex, multi-mode lasing in broad-area semiconductor diode lasers. The lateral spatial distribution of laser energy is further complicated by an optical nonlinearity in the semiconductor laser gain region, due to the dependence of the refractive index on the free-charge carrier density. This nonlinearity is responsible for the self-deformation of the lateral field distribution, so that in the lateral direction, the active region has areas of higher and lower light intensity, often called filaments. This highly-nonuniform lateral field distribution results in poor beam quality and hot-spot facet damage at relatively low output power for typical broad-area semiconductor diode lasers. This dissertation proposes and analyzes a specific approach to suppress filamentation in broad-area semiconductor diode lasers, with the general goal of increasing the laser power that can be produced while retaining good beam quality. The analysis approach is based on a six-wave mixing methodology for the evaluation of filamentation in general broad-area semiconductor diode laser structures. This methodology is first applied to examine the growth of filamentation in typical broad-area semiconductor diode laser designs. A specific design modification to a broad-area laser

  12. Laser-based irradiation apparatus and methods for monitoring the dose-rate response of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2006-03-28

    A scanned, pulsed, focused laser irradiation apparatus can measure and image the photocurrent collection resulting from a dose-rate equivalent exposure to infrared laser light across an entire silicon die. Comparisons of dose-rate response images or time-delay images from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems allows precise identification of those specific age-affected circuit structures within a device that merit further quantitative analysis with targeted materials or electrical testing techniques. Another embodiment of the invention comprises a broad-beam, dose rate-equivalent exposure apparatus. The broad-beam laser irradiation apparatus can determine if aging has affected the device's overall functionality. This embodiment can be combined with the synchronized introduction of external electrical transients into a device under test to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure.

  13. Heteroclinic dynamics of coupled semiconductor lasers with optoelectronic feedback.

    PubMed

    Shahin, S; Vallini, F; Monifi, F; Rabinovich, M; Fainman, Y

    2016-11-15

    Generalized Lotka-Volterra (GLV) equations are important equations used in various areas of science to describe competitive dynamics among a population of N interacting nodes in a network topology. In this Letter, we introduce a photonic network consisting of three optoelectronically cross-coupled semiconductor lasers to realize a GLV model. In such a network, the interaction of intensity and carrier inversion rates, as well as phases of laser oscillator nodes, result in various dynamics. We study the influence of asymmetric coupling strength and frequency detuning between semiconductor lasers and show that inhibitory asymmetric coupling is required to achieve consecutive amplitude oscillations of the laser nodes. These studies were motivated primarily by the dynamical models used to model brain cognitive activities and their correspondence with dynamics obtained among coupled laser oscillators.

  14. Laser interferometric method for determining the carrier diffusion length in semiconductors

    SciTech Connect

    Manukhov, V. V.; Fedortsov, A. B.; Ivanov, A. S.

    2015-09-15

    A new laser interferometric method for measuring the carrier diffusion length in semiconductors is proposed. The method is based on the interference–absorption interaction of two laser radiations in a semiconductor. Injected radiation generates additional carriers in a semiconductor, which causes a change in the material’s optical constants and modulation of the probing radiation passed through the sample. When changing the distance between carrier generation and probing points, a decrease in the carrier concentration, which depends on the diffusion length, is recorded. The diffusion length is determined by comparing the experimental and theoretical dependences of the probe signal on the divergence of the injector and probe beams. The method is successfully tested on semiconductor samples with different thicknesses and surface states and can be used in scientific research and the electronics industry.

  15. Reliability of Semiconductor Laser Packaging in Space Applications

    NASA Technical Reports Server (NTRS)

    Gontijo, Ivair; Qiu, Yueming; Shapiro, Andrew A.

    2008-01-01

    A typical set up used to perform lifetime tests of packaged, fiber pigtailed semiconductor lasers is described, as well as tests performed on a set of four pump lasers. It was found that two lasers failed after 3200, and 6100 hours under device specified bias conditions at elevated temperatures. Failure analysis of the lasers indicates imperfections and carbon contamination of the laser metallization, possibly from improperly cleaned photo resist. SEM imaging of the front facet of one of the lasers, although of poor quality due to the optical fiber charging effects, shows evidence of catastrophic damage at the facet. More stringent manufacturing controls with 100% visual inspection of laser chips are needed to prevent imperfect lasers from proceeding to packaging and ending up in space applications, where failure can result in the loss of a space flight mission.

  16. 80 nm tunable DBR-free semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Albrecht, A. R.; Cederberg, J. G.; Sheik-Bahae, M.

    2016-07-01

    We report a widely tunable optically pumped distributed Bragg reflector (DBR)-free semiconductor disk laser with 6 W continuous wave output power near 1055 nm when using a 2% output coupler. Using only high reflecting mirrors, the lasing wavelength is centered at 1034 nm and can be tuned up to a record 80 nm by using a birefringent filter. We attribute such wide tunability to the unique broad effective gain bandwidth of DBR-free semiconductor disk lasers achieved by eliminating the active mirror geometry.

  17. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

    1991-01-01

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet.

  18. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G.R.; Hohimer, J.P.; Owyoung, A.

    1991-02-19

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet. 18 figures.

  19. A 3000W 808nm QCW G-stack semiconductor laser array

    NASA Astrophysics Data System (ADS)

    Zhang, Pu; Wang, Jingwei; Hou, Dong; Wang, Zhenfu; Xiong, Lingling; Liu, Hui; Nie, Zhiqiang; Liu, Xingsheng

    2015-02-01

    With the improvement of output power, efficiency and reliability, high power semiconductor lasers have been applied in more and more fields. In this paper, a conduction-cooled, high peak output power semiconductor laser array was studied and developed. The structure and operation parameters of G-Stack semiconductor laser array were designed and optimized using finite element method (FEM). A Quasi-continuous-wave (QCW) conduction-cooled G-Stack semiconductor laser array with a narrow spectrum width was fabricated successfully.

  20. Deep-red semiconductor monolithic mode-locked lasers

    SciTech Connect

    Kong, L.; Bajek, D.; White, S. E.; Forrest, A. F.; Cataluna, M. A.; Wang, H. L.; Pan, J. Q.; Wang, X. L.; Cui, B. F.; Ding, Y.

    2014-12-01

    A deep-red semiconductor monolithic mode-locked laser is demonstrated. Multi-section laser diodes based on an AlGaAs multi-quantum-well structure were passively mode-locked, enabling the generation of picosecond optical pulses at 752 nm, at pulse repetition rates of 19.37 GHz. An investigation of the dependence of the pulse duration as a function of reverse bias revealed a predominantly exponential decay trend of the pulse duration, varying from 10.5 ps down to 3.5 ps, which can be associated with the concomitant reduction of absorption recovery time with increasing applied field. A 30-MHz-tunability of the pulse repetition rate with bias conditions is also reported. The demonstration of such a compact, efficient and versatile ultrafast laser in this spectral region paves the way for its deployment in a wide range of applications such as biomedical microscopy, pulsed terahertz generation as well as microwave and millimeter-wave generation, with further impact on sensing, imaging and optical communications.

  1. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    SciTech Connect

    Chamorovskiy, A Yu; Okhotnikov, Oleg G

    2012-11-30

    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  2. Phase stability of injection-locked beam of semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Kwon, Jin Hyuk; Kim, Do Hoon; Schuster, Gregory; Lee, Ja H.

    1992-01-01

    An experiment on the phase stability of an injection locked beam was done by using AlGaAs semiconductor lasers. The coherence of two beams from master and slave lasers was measured by interference between the beams in the Twymann-Green interferometer. The phase change of the output beam of the slave laser as a function of the driving current was measured in a Mach-Zehnder interferometer consisting of the master and slave lasers, and a value of 2.5 radians/mA was obtained.

  3. Dynamics of Semiconductor Microcavities Using Ultrashort Pulse Lasers

    NASA Astrophysics Data System (ADS)

    Rhee, June-Koo

    1995-01-01

    Using femtosecond optical spectroscopy, we perform an extensive study of dynamics of an AlAs/AlGaAs/GaAs-based semiconductor quantum microcavity, which exhibit cavity -polariton behavior owing to strong coupling between the exciton and cavity modes. We explore the dynamics of time -domain vacuum Rabi oscillations, the spatial coherence transfer of cavity-polariton states, and cavity-polariton dynamics in the nonlinear regime. In the time domain, when the microcavity is impulsively excited by a short coherent optical pulse, we observe the vacuum Rabi oscillations in the radiation, corresponding to the cavity-polariton mode splitting of the microcavity. Interferometric pump-probe measurements clearly show the coherent evolution of the cavity-polaritons. At high intensity, the normal mode splitting collapses due to bleaching of the excitonic oscillator strength. The dynamics of the splitting reveal the momentum relaxation of the cavity-polaritons due to inhomogeneous broadening, and provides evidence for delayed exciton-exciton scattering due to vacuum Rabi oscillation. When the cavity is excited coherently at an oblique angle, we also observe coherent radiation in the normal direction of the substrate, with a nearly fixed delay of 450 fs. This radiation is coherent with the excitation pulse and dependent on excitation density. Specifically, the initially-excited spatial cavity-polariton state is coherently transferred to the other spatial state selected by the cavity mode. The excitation dependence suggests this coherence transfer is associated with exciton scatterings. A density-matrix analysis for two cavity-polariton systems shows our model is in good qualitative agreement with the experiment. In order to perform femtosecond semiconductor spectroscopic experiments, it was necessary to develop the ultrafast laser source. We describe a cw-argon-laser -pumped Ti:sapphire laser system and a real-time femtosecond -optical-pulse analyzer, for femtosecond spectroscopy

  4. Researching the 915 nm high-power and high-brightness semiconductor laser single chip coupling module

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Wang, Cuiluan; Wu, Xia; Zhu, Lingni; Jing, Hongqi; Ma, Xiaoyu; Liu, Suping

    2017-02-01

    Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality of the laser diode is very poor, the 915 nm laser diode is generally based on optical fiber coupling module to output the laser. Using the beam-shaping and fiber-coupling technology to improve the quality of output beam light, we present a kind of high-power and high-brightness semiconductor laser module, which can output 13.22 W through the optical fiber. Based on 915 nm GaAs semiconductor laser diode which has output power of 13.91 W, we describe a thoroughly detailed procedure for reshaping the beam output from the semiconductor laser diode and coupling the beam into the optical fiber of which the core diameter is 105 μm and the numerical aperture is 0.18. We get 13.22 W from the output fiber of the module at 14.5 A, the coupling efficiency of the whole module is 95.03% and the brightness is 1.5 MW/cm2 -str. The output power of the single chip semiconductor laser module achieves the advanced level in the domestic use.

  5. Zinc oxide based diluted magnetic semiconductor nanoparticles: Synthesis by laser ablation in liquids, microstructural and optical properties

    SciTech Connect

    Savchuk, Andriy I.; Stolyarchuk, Ihor D.; Savchuk, Oleksandr A.; Makoviy, Vitaliy V.; Smolinsky, Mykhailo M.; Shporta, Oleksandra A.; Perrone, Alessio

    2013-12-04

    Nanoparticles of ZnO and ZnO doped with transition metals (Mn, Co) were synthesized by laser ablation in liquid medium. Scanning electron microscopy (SEM) showed formation of nanostructures with different shapes. Atomic force microscopy (AFM) gives information about surface morphology of the formed nanostructures. Absorption edge of ZnO, ZnO:Mn and ZnO:Co colloidal nanoparticles exhibits blue shift due to confinement effect. In photoluminescence spectra three peaks are attributed to the band-edge transitions and defect states. The Faraday rotation in ZnO:Mn nanoparticles gives evidence for paramagnetic behavior at room temperature.

  6. All semiconductor laser Doppler anemometer at 1.55 microm.

    PubMed

    Hansen, René Skov; Pedersen, Christian

    2008-10-27

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz.

  7. Recent progress in picosecond pulse generation from semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    This paper reviews the recent progress in producing picosecond optical pulses from semiconductor laser diodes. The discussion concentrates on the mode-locking of a semiconductor laser diode in an external resonator. Transform-limited optical pulses ranging from several picoseconds to subpicosecond durations have been observed with active and passive mode-locking. Even though continuing research on the influence of impurities and defects on the mode-locking process is still needed, this technique has good promise for being utilized in fiber-optic communication systems. Alternative methods of direct electrical and optical excitation to produce ultrashort laser pulses are also described. They can generate pulses of similar widths to those obtained by mode-locking. The pulses generated will find applications in laser ranging and detector response measurement.

  8. Fast random number generation with spontaneous emission noise of a single-mode semiconductor laser

    NASA Astrophysics Data System (ADS)

    Zhang, Jianzhong; Zhang, Mingjiang; Liu, Yi; Li, Pu; Yi, Xiaogang; Zhang, Mingtao; Wang, Yuncai

    2016-11-01

    We experimentally demonstrate a 12.5 Gb s-1 random number generator based on measuring the spontaneous emission noise of a single-mode semiconductor laser. The spontaneous emission of light is quantum mechanical in nature and is an inborn physical entropy source of true randomness. By combining a high-speed analog-to-digital converter and off-line processing, random numbers are extracted from the spontaneous emission with the verified randomness. The generator is simple, robust, and with no need of accurately tuning the comparison threshold. The use of semiconductor lasers makes it particularly compatible with the delivery of random numbers in optical networks.

  9. Photoelectrolysis of water at high current density - Use of laser light excitation of semiconductor-based photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Bocarsley, A. B.; Bolts, J. M.

    1978-01-01

    In the present paper, some results are given for UV laser light irradiation of the photoanode (SnO2, SrTiO3, or TiO2) in a cell for the light-driven electrolysis of H2O, at radiation intensities of up to 380 W/sq cm. The properties of the anode material are found to be independent of light intensity. Conversion of UV light to stored chemical energy in the form of 2H2/O2 from H2O was driven at a rate of up to 30 W/sq cm. High O2 evolution rates at the irradiated anodes without changes in the current-voltage curves are attributed to the excess oxidizing power associated with photogenerated holes. A test for this sort of hypothesis for H2 evolution at p-type materials is proposed.

  10. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Refractive indices of superlattices made of III-V semiconductor compounds and their solid solutions and semiconductor waveguide laser structures

    NASA Astrophysics Data System (ADS)

    Unger, K.

    1988-11-01

    An analysis is made of the theoretical problems encountered in precision calculations of refractive indices of semiconductor materials arising in connection with the use of superlattices as active layers in double-heterostructure lasers and in connection with the use of the impurity-induced disordering effect, i.e., the ability to transform selectively a superlattice into a corresponding solid solution. This can be done by diffusion or ion implantation. A review is given of calculations of refractive indices based on the knowledge of the energy band structure and the role of disorder is considered particularly. An anomaly observed in the (InAl)As system is considered. It is shown that the local field effects and exciton transitions are important. A reasonable approach is clearly a direct calculation of the difference between the refractive indices of superlattices based on compounds and of those based on their solid solutions.

  11. Semiconductor lasers vs LEDs in diagnostic and therapeutic medicine

    NASA Astrophysics Data System (ADS)

    Gryko, Lukasz; Zajac, Andrzej; Szymanska, Justyna; Blaszczak, Urszula; Palkowska, Anna; Kulesza, Ewa

    2016-12-01

    Semiconductor emitters are used in many areas of medicine, allowing for new methods of diagnosis, treatment and effective prevention of many diseases. The article presents selected areas of application of semiconductor sources in UVVIS- NIR range, where in recent years competition in semiconductor lasers and LEDs applications has been observed. Examples of applications of analyzed sources are indicated for LLLT, PDT and optical diagnostics using the procedure of color contrast. Selected results of LLLT research of the authors are presented that were obtained by means of the developed optoelectronic system for objectified irradiation and studies on the impact of low-energy laser and LED on lines of endothelial cells of umbilical vein. Usefulness of the spectrally tunable LED lighting system for diagnostic purposes is also demonstrated, also as an illuminator for surface applications - in procedure of variable color contrast of the illuminated object.

  12. Direct solar pumping of semiconductor lasers: A feasibility study

    NASA Technical Reports Server (NTRS)

    Anderson, Neal G.

    1991-01-01

    The primary goals of the feasibility study are the following: (1) to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space directly focused sunlight; and (2) to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or battery electrically pumping a current injection laser. With external modulation, such lasers may prove to be efficient sources for intersatellite communications. We proposed to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation for operation at low pump intensities. This report outlines our progress toward these goals. Discussion of several technical details are left to the attached summary abstract.

  13. Visible light surface emitting semiconductor laser

    DOEpatents

    Olbright, Gregory R.; Jewell, Jack L.

    1993-01-01

    A vertical-cavity surface-emitting laser is disclosed comprising a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers surrounding one or more active, optically emitting quantum-well layers having a bandgap in the visible which serve as the active optically emitting material of the device. The thickness of the laser cavity is m .lambda./2n.sub.eff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and n.sub.eff is the effective index of refraction of the cavity. Electrical pumping of the laser is achieved by heavily doping the bottom mirror and substrate to one conductivity-type and heavily doping regions of the upper mirror with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Specific embodiments of the invention for generating red, green, and blue radiation are described.

  14. III-V Semiconductor Quantum Well Lasers and Related Optoelectronic Devices (On Silicon). Oxide-Defined Semiconductor Quantum Well Lasers and Optoelectrnic Devices: A1-Based III-V Native Oxides

    DTIC Science & Technology

    1992-05-01

    lateral direction. guide layer. The effect of the optical waveguide is shown by the The laser fabrication begins with the deposition on the near-field...to manipulate photons around a "chip," e.g., The laser fabrication begins with the patterning of for optoelectronic integrated circuits (OEICs), a

  15. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Injection lasers based on the AlGaAsSb system emitting at 1.6 μm

    NASA Astrophysics Data System (ADS)

    Virro, A. L.; Eliseev, P. G.; Lyuk, P. A.; Fridental, Ya K.; Khaller, Yu E.

    1988-11-01

    An experimental dependence of the threshold current density jth on the thickness of the active region was used to find the reduced threshold current density for AlGaAsSb (λ = 1.59μm, T = 295K) lasers: this density was 8 kA·cm-2·μm-1. The minimum threshold current was jth = 1.8 kA/cm2. Wide-contact lasers exhibited cw operation down to 175 K.

  16. Particle-free semiconductor cutting using the water jet guided laser

    NASA Astrophysics Data System (ADS)

    Perrottet, Delphine; Spiegel, Akos; Wagner, Frank; Housh, Roy; Richerzhagen, Bernold; Manley, John

    2005-04-01

    For many years, wafer cutting has posed a challenge to laser-based cutting techniques because of the brittle nature of semiconductors and the exacting requirements for cleanliness. Since conventional laser cutting generates a strong heat-affected zone and a large amount of particles, abrasive sawing is currently the standard process for semiconductor wafer dicing. However, abrasive sawing can no longer fulfill the demands of new, emerging types of semiconductor devices like those based on thin wafers and compound semiconductors. New separation methods are investigated here. The water jet guided laser is a relatively recent technology that offers not only a significantly reduced heat-affected zone but also a cleaner wafer surface. This is due, first, to the water jet, which cools the material between the laser pulses and removes a significant amount of molten material generated by laser ablation. However, the system has recently been upgraded by adding a device that covers the entire wafer surface with a well-controlled thin water film throughout the cutting process. The few generated particles are thus kept in suspension and will not deposit on the wafer surface.

  17. Reactive Ion Etched Unstable and Stable Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Biellak, Stephen Alexander

    1995-01-01

    High power, diffraction-limited semiconductor laser diodes are desirable for numerous applications such as efficient solid state laser pumping, nonlinear frequency conversion, and free-space communication. In the past several years, wide-stripe diode lasers and laser arrays with powers of up to several watts have become commercially available, but the beam quality of these devices is generally poor due to filamentation, a nonlinear material effect that aberrates the output beam profile. An attractive alternative to these simple Fabry-Perot lasers is offered by unstable resonators, which have inherently large gain volumes and a cavity geometry that inhibits filamentation. Prototype unstable resonators with dry-etched cavity mirrors have recently been demonstrated to achieve near diffraction -limited operation at moderately high output powers. However, the lateral mode properties of unstable resonators have heretofore not been examined in detail, nor has a reliable, high-throughput mirror etch process been developed for these devices. In this work, we have developed a GaAs RIE etching technique using common process equipment that yields mirrors with RMS surface roughness of 3 to 5 nm. We have fabricated unstable resonators and have measured lateral M ^2 beam quality values as low as 1.25 at 300 mW single facet output power in high magnification devices. The impact of cavity geometry and processing techniques on device performance was studied, and the optimal parameters for high-brightness applications were determined. Nearly concentric stable-resonator diode lasers were also fabricated for the first time using this etching technique. These stable-resonators were observed to operate in lateral modes determined primarily by the physical resonator structure up to several times threshold, after which nonlinear effects dominated the cavity modes. Based on these measurements, a description of stable device behavior in terms of gain saturation was developed. Finally, a

  18. Study of the absorption coefficient in layers of a semiconductor laser heterostructure

    SciTech Connect

    Veselov, D A; Pikhtin, N A; Lyutetskiy, A V; Nikolaev, D N; Slipchenko, S O; Sokolova, Z N; Shamakhov, V V; Shashkin, I S; Voronkova, N V; Tarasov, I S

    2015-07-31

    A method of studying the absorption coefficient in layers of semiconductor lasers is proposed. Using lasers based on MOVPE-grown separate-confinement heterostructures with a broadened waveguide, the absorption coefficient is investigated under pulsed current pumping. It is found that when the pump current flows through the laser in question, an additional internal optical absorption arises in the heterostructure layers. It is shown that an increase in the pump current density up to 20 kA cm{sup -2} leads to an increase in absorption up to 2.5 cm{sup -1}. The feasibility of studying free-carrier absorption in the active region is demonstrated. (lasers)

  19. 115 kHz tuning repetition rate ultrahigh-speed wavelength-swept semiconductor laser.

    PubMed

    Oh, W Y; Yun, S H; Tearney, G J; Bouma, B E

    2005-12-01

    We demonstrate an ultrahigh-speed wavelength-swept semiconductor laser using a polygon-based wavelength scanning filter. With a polygon rotational speed of 900 revolutions per second, a continuous wavelength tuning rate of 9200 nm/ms and a tuning repetition rate of 115 kHz were achieved. The wavelength tuning range of the laser was 80 nm centered at 1325 nm, and the average polarized output power was 23 mW.

  20. Substrate-emitting semiconductor laser with a trapezoidal active region

    SciTech Connect

    Dikareva, N V; Nekorkin, S M; Karzanova, M V; Zvonkov, B N; Aleshkin, V Ya; Dubinov, A A; Afonenko, A A

    2014-04-28

    Semiconductor lasers with a narrow (∼2°) directional pattern in the planes both parallel and perpendicular to the p–n junction are fabricated. To achieve a low radiation divergence in the p–n junction plane, the active region in this plane was designed in the form of a trapezium. The narrow directional pattern in the plane perpendicular to the p–n junction was ensured by the use of a leaky mode, through which more than 90% of laser power was coupled out. (lasers)

  1. Correlation dimension signature of wideband chaos synchronization of semiconductor lasers.

    PubMed

    Kane, D M; Toomey, J P; Lee, M W; Shore, K A

    2006-01-01

    Chaos data analysis has been performed on the chaotic output power time series data from a synchronized transmitter-receiver pair of semiconductor lasers. The system uses an asymmetric, bidirectional coupling configuration between the master (transmitter), which is a laser diode with optical feedback, and a stand-alone slave semiconductor laser. The correlation dimension of the chaotic time series has a minimum value of 4, which was obtained from high-bandwidth measurements. The correlation dimensions for both the master and the synchronized slave are identical when the cross-correlation coefficient of the synchronized chaos is above 0.9. These results establish correlation dimension analysis as an effective tool for the determination of the quality of wideband chaos synchronization.

  2. Phase instabilities in semiconductor lasers: A codimension-2 analysis

    NASA Astrophysics Data System (ADS)

    Gil, L.; Lippi, G. L.

    2014-11-01

    We compute the normal form description of a semiconductor laser near its threshold, with the sole assumption that the polarization be related to the electric field through the susceptibility (dependent on laser frequency and population inversion). We prove both analytically and numerically the possible existence of a phase-unstable regime, characterized by a periodic oscillation of the optical frequency and a constant intensity. This regime bears close resemblance to the mode-switching behavior, with constant total output power, experimentally observed in semiconductor lasers. In addition, our model predicts the appearance of a phase- and amplitude-turbulent regime, compatible with experimental observations. Both regimes are well known in fluid dynamics under the name Benjamin-Feir instability.

  3. High Intensity Laser Interactions with Narrow Gap Semiconductors

    NASA Astrophysics Data System (ADS)

    Hasselback, Michael Peter

    1995-01-01

    Two-photon absorption in solids is a well known and thoroughly characterized nonlinear optical process. Higher order multi-photon absorption however, has received comparatively little study. In this dissertation, results of experiments with bulk, narrow gap semiconductors InSb and InAs are reported. By performing Z-scans and pump-probe measurements at different laser wavelengths and sample temperatures, various nonlinear optical processes are identified. Data obtained with InAs is consistent with photocarrier generation by three and four-photon absorption. It is believed this is the first direct evidence of four-photon absorption in a semiconductor. Leakage two-photon is observed with InSb at 15K. This novel effect arises from dynamic band un-blocking caused by laser heating of conduction electrons. All phenomena are excited with picosecond CO_2 laser pulses at irradiances below the material damage threshold. Physical models describing the observations are presented.

  4. Semiconductor laser devices having lateral refractive index tailoring

    DOEpatents

    Ashby, Carol I. H.; Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

    1990-01-01

    A broad-area semiconductor laser diode includes an active lasing region interposed between an upper and a lower cladding layer, the laser diode further comprising structure for controllably varying a lateral refractive index profile of the diode to substantially compensate for an effect of junction heating during operation. In embodiments disclosed the controlling structure comprises resistive heating strips or non-radiative linear junctions disposed parallel to the active region. Another embodiment discloses a multi-layered upper cladding region selectively disordered by implanted or diffused dopant impurities. Still another embodiment discloses an upper cladding layer of variable thickness that is convex in shape and symmetrically disposed about a central axis of the active region. The teaching of the invention is also shown to be applicable to arrays of semiconductor laser diodes.

  5. Semiconductor laser theory with many-body effects

    SciTech Connect

    Haug, H.; Gayg, G.; Koch, S.W.

    1989-02-15

    A description of the electron-hole plasma of a semiconductor laser is developed that includes the many-body effects due to the Coulomb interactions. In particular, the plasma density-dependent band-gap renormalization, the broadening due to intraband scattering, and the Coulomb enhancement are included and evaluated for three- and two-dimensional semiconductor structures. Because of the short intraband scattering relaxation time one can eliminate the interband polarization adiabatically and at the same time introduce a hydrodynamic description of the interband kinetics. From this general formulation a diffusion equation for the carrier density is derived. The resulting ambipolar diffusion coefficient decreases with the laser intensity due to the reduction of the electron drift. The present semiclassical theory is completed by the laser field equations and by the addition of Langevin fluctuations.

  6. Femtosecond Laser Processing of Wide Bandgap Semiconductors and Their Applications

    NASA Astrophysics Data System (ADS)

    Phillips, Katherine Collett Furr

    This thesis explores the production, characterization, and water oxidation efficiency of wide bandgap semiconductors made through femtosecond-laser irradiation of various materials. Our investigation focuses on three main aspects: 1) producing titanium dioxide (TiO2) from titanium metal, 2) using our laser-made materials in a photoelectrochemical cell for water oxidation, and 3) utilizing the femtosecond laser to create a variety of other mixed metal oxides for further water oxidation studies and biological applications. We first discuss producing TiO2 and titanium nitride. We report that there is chemical selectivity at play in the femtosecond laser doping process so not all dopants in the surrounding atmosphere will necessarily be incorporated. We then show that the material made from laser-irradiation of titanium metal, when annealed, has a three-fold enhancement in overall water oxidation when irradiated with UV light. We attribute this enhancement through various material characterization methods to the creation of a more pure form of rutile TiO2 with less defects. We then present a variety of studies done with doping both TiO2 and other oxides with broadband photoelectrochemistry and offer that the dopant incorporation hurts the overall water oxidation rate. Lastly, we use the laser-treated titanium to test cell adhesion and viability. Our results demonstrate an ability to femtosecond-laser process semiconductors to produce materials that no one has made previously and study their properties using collaborations across chemistry and biology, yielding true interdisciplinary research.

  7. Investigation of Semiconductor Lasers for Wideband Recording

    DTIC Science & Technology

    1975-03-01

    area should be directed towards: 1.) replacing the rotating scanner mirror with an acousto - optic deflector ,and 2 .) invest- igating recording with...developed, high efficiency, acousto - optic deflectors could replace the scanning mirror, allowing the construction of an all solid state laser...MMMMi rilM^aiHlifil ̂ id ŗ" ■ " III_IIMIiipmiiu upiiuii|.aippi lll|ll|.ilIJIIU|||IIW|llf.Lllll«l|llll "^ laser, an acousto optic deflector , and

  8. Record performance of electrical injection sub-wavelength metallic-cavity semiconductor lasers at room temperature.

    PubMed

    Ding, K; Hill, M T; Liu, Z C; Yin, L J; van Veldhoven, P J; Ning, C Z

    2013-02-25

    We demonstrate a continuous wave (CW) sub-wavelength metallic-cavity semiconductor laser with electrical injection at room temperature (RT). Our metal-cavity laser with a cavity volume of 0.67λ3 (λ = 1591 nm) shows a linewidth of 0.5 nm at RT, which corresponds to a Q-value of 3182 compared to 235 of the cavity Q, the highest Q under lasing condition for RT CW operation of any sub-wavelength metallic-cavity laser. Such record performance provides convincing evidences of the feasibility of RT CW sub-wavelength metallic-cavity lasers, thus opening a wide range of practical possibilities of novel nanophotonic devices based on metal-semiconductor structures.

  9. Semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  10. Metal-optic and Plasmonic Semiconductor-based Nanolasers

    NASA Astrophysics Data System (ADS)

    Lakhani, Amit Manmohan

    Over the past few decades, semiconductor lasers have relentlessly followed the path towards miniaturization. Smaller lasers are more energy efficient, are cheaper to make, and open up new applications in sensing and displays, among many other things. Yet, up until recently, there was a fundamental problem with making lasers smaller: purely semiconductor lasers couldn't be made smaller than the diffraction limit of light. In recent years, however, metal-based lasers have been demonstrated in the nanoscale that have shattered the diffraction limit. As optical materials, metals can be used to either reflect light (metal-optics) or convert light to electrical currents (plasmonics). In both cases, metals have provided ways to squeeze light beyond the diffraction limit. In this dissertation, I experimentally demonstrated one nanolaser based on plasmonic transduction and another laser based on metal-optic reflection. To create coherent plasmons, I designed a nanolaser based on a plasmonic bandgap defect state inside a surface plasmonic crystal. In a one-dimensional periodic semiconductor beam, I was able to confine surface plasmons by interrupting the periodicity of the crystal. These confined surface plasmons then underwent laser oscillations in effective mode volumes as small as 0.007 cubic wavelengths. At this electromagnetic volume, energy was squeezed 10 times smaller than those possible in similar photonic crystals that do not utilize metal. This demonstration should pave the way for achieving engineered nanolasers with deep-subwavelength mode volumes and enable plasmonic crystals to become attractive platforms for designing plasmons. After achieving large reductions in electromagnetic mode volumes, I switched to a metal-optics-based nanolaser design to further reduce the physical volumes of small light sources. The semiconductor nanopatch laser achieved laser oscillations with subwavelength-scale physical dimensions (0.019 cubic wavelengths) and effective mode

  11. N.G. Basov and early works on semiconductor lasers at P.N. Lebedev Physics Institute

    SciTech Connect

    Eliseev, P G

    2012-12-31

    A survey is presented of works on creation and investigation of semiconductor lasers during 1957 - 1977 at the P.N. Lebedev Physics Institute. Many of these works were initiated by N.G. Basov, starting from pre-laser time, when N.G. Basov and his coworkers formulated principal conditions of creation of lasers on interband transitions in semiconductors. Main directions of further works were diode lasers based on various materials and structures, their characteristics of output power, high-speed operation and reliability. (special issue devoted to the 90th anniversary of n.g. basov)

  12. Synchronous characterization of semiconductor microcavity laser beam.

    PubMed

    Wang, T; Lippi, G L

    2015-06-01

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

  13. Synchronous characterization of semiconductor microcavity laser beam

    SciTech Connect

    Wang, T. Lippi, G. L.

    2015-06-15

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam’s tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

  14. Wavelength-resonant surface-emitting semiconductor laser

    DOEpatents

    Brueck, Steven R. J.; Schaus, Christian F.; Osinski, Marek A.; McInerney, John G.; Raja, M. Yasin A.; Brennan, Thomas M.; Hammons, Burrell E.

    1989-01-01

    A wavelength resonant semiconductor gain medium is disclosed. The essential feature of this medium is a multiplicity of quantum-well gain regions separated by semiconductor spacer regions of higher bandgap. Each period of this medium consisting of one quantum-well region and the adjacent spacer region is chosen such that the total width is equal to an integral multiple of 1/2 the wavelength in the medium of the radiation with which the medium is interacting. Optical, electron-beam and electrical injection pumping of the medium is disclosed. This medium may be used as a laser medium for single devices or arrays either with or without reflectors, which may be either semiconductor or external.

  15. High-power MIXSEL: an integrated ultrafast semiconductor laser with 6.4 W average power.

    PubMed

    Rudin, B; Wittwer, V J; Maas, D J H C; Hoffmann, M; Sieber, O D; Barbarin, Y; Golling, M; Südmeyer, T; Keller, U

    2010-12-20

    High-power ultrafast lasers are important for numerous industrial and scientific applications. Current multi-watt systems, however, are based on relatively complex laser concepts, for example using additional intracavity elements for pulse formation. Moving towards a higher level of integration would reduce complexity, packaging, and manufacturing cost, which are important requirements for mass production. Semiconductor lasers are well established for such applications, and optically-pumped vertical external cavity surface emitting lasers (VECSELs) are most promising for higher power applications, generating the highest power in fundamental transverse mode (>20 W) to date. Ultrashort pulses have been demonstrated using passive modelocking with a semiconductor saturable absorber mirror (SESAM), achieving for example 2.1-W average power, sub-100-fs pulse duration, and 50-GHz pulse repetition rate. Previously the integration of both the gain and absorber elements into a single wafer was demonstrated with the MIXSEL (modelocked integrated external-cavity surface emitting laser) but with limited average output power (<200 mW). We have demonstrated the power scaling concept of the MIXSEL using optimized quantum dot saturable absorbers in an antiresonant structure design combined with an improved thermal management by wafer removal and mounting of the 8-µm thick MIXSEL structure directly onto a CVD-diamond heat spreader. The simple straight cavity with only two components has generated 28-ps pulses at 2.5-GHz repetition rate and an average output power of 6.4 W, which is higher than for any other modelocked semiconductor laser.

  16. Colorless WDM-PON based on a Fabry-Pérot laser diode and reflective semiconductor optical amplifiers for simultaneous transmission of bidirectional gigabit baseband signals and broadcasting signal.

    PubMed

    Pham, Thang Tien; Kim, Hyun-Seung; Won, Yong-Yuk; Han, Sang-Kook

    2009-09-14

    A novel WDM-PON system delivering bidirectional baseband data and broadcasting data is proposed and demonstrated. A subcarrier multiplexing signal is broadcasted to all users by modulating a broadband optical source based on a Fabry-Pérot laser diode. Reflective semiconductor optical amplifiers are used as colorless modulators for the baseband data at both optical line terminal and remote optical network units. Transmission performance including bit error rate of bidirectional gigabit data and error vector magnitude of broadcasting data of many optical channels is investigated. Additionally, the data rate for the broadcasting signal was improved by using an external modulator.

  17. Excitability in a quantum dot semiconductor laser with optical injection.

    PubMed

    Goulding, D; Hegarty, S P; Rasskazov, O; Melnik, S; Hartnett, M; Greene, G; McInerney, J G; Rachinskii, D; Huyet, G

    2007-04-13

    We experimentally analyze the dynamics of a quantum dot semiconductor laser operating under optical injection. We observe the appearance of single- and double-pulse excitability at one boundary of the locking region. Theoretical considerations show that these pulses are related to a saddle-node bifurcation on a limit cycle as in the Adler equation. The double pulses are related to a period-doubling bifurcation and occur on the same homoclinic curve as the single pulses.

  18. Refractory period of an excitable semiconductor laser with optical injection

    NASA Astrophysics Data System (ADS)

    Garbin, B.; Dolcemascolo, A.; Prati, F.; Javaloyes, J.; Tissoni, G.; Barland, S.

    2017-01-01

    Injection-locked semiconductor lasers can be brought to a neuronlike excitable regime when parameters are set close to the unlocking transition. Here we study experimentally the response of this system to repeated optical perturbations and observe the existence of a refractory period during which perturbations are not able to elicit an excitable response. The results are analyzed via simulations of a set of dynamical equations which reproduced adequately the experimental results.

  19. Analytical model of spin-polarized semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Gøthgen, Christian; Oszwałdowski, Rafał; Petrou, Athos; Žutić, Igor

    2008-07-01

    We formulate an analytical model for semiconductor lasers with injection (pump) of spin-polarized electrons, allowing us to systematically investigate different operating regimes. We demonstrate that the maximum threshold reduction by electrically pumped spin-polarized carriers is larger than previously thought possible and, surprisingly, can be enhanced by ultrafast spin relaxation of holes. We reveal how different modes of carrier recombination directly affect the threshold reduction. Neither spin-up nor spin-down electron populations are separately clamped (pinned) near the threshold, where such lasers can act as effective nonlinear filters of circularly polarized light, owing to their spin-dependent gain.

  20. High density semiconductor nanodots by direct laser fabrication

    NASA Astrophysics Data System (ADS)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    We report a direct method of fabricating high density nanodots on the GaAs(001) surfaces using laser irradiations on the surface. Surface images indicate that the large clumps are not accompanied with the formation of nanodots even though its density is higher than the critical density above which detrimental large clumps begin to show up in the conventional Stranski-Krastanov growth technique. Atomic force microscopy is used to image the GaAs(001) surfaces that are irradiated by high power laser pulses interferentially. The analysis suggests that high density quantum dots be fabricated directly on semiconductor surfaces.

  1. Sensitivity of quantum-dot semiconductor lasers to optical feedback.

    PubMed

    O'Brien, D; Hegarty, S P; Huyet, G; Uskov, A V

    2004-05-15

    The sensitivity of quantum-dot semiconductor lasers to optical feedback is analyzed with a Lang-Kobayashi approach applied to a standard quantum-dot laser model. The carriers are injected into a quantum well and are captured by, or escape from, the quantum dots through either carrier-carrier or phonon-carrier interaction. Because of Pauli blocking, the capture rate into the dots depends on the carrier occupancy level in the dots. Here we show that different carrier capture dynamics lead to a strong modification of the damping of the relaxation oscillations. Regions of increased damping display reduced sensitivity to optical feedback even for a relatively large alpha factor.

  2. Ultrashort pulse laser slicing of semiconductor crystal

    NASA Astrophysics Data System (ADS)

    Kim, Eunho; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Miura, Kiyotaka

    2016-07-01

    Meanwhile, by the convention wire-saw technique, it is difficult to slice off a thin wafer from bulk SiC crystal without the reserving space for cutting. In this study, we have achieved exfoliation of 4H-SiC single crystal by femtosecond laser induced slicing method. By using this, the exfoliated surface with the root-mean-square roughness of 3 μm and the cutting-loss thickness smaller than 30 μm was successfully demonstrated. We have also observed the nanostructure on the exfoliated surface in SiC crystal.

  3. rf-microwave switches based on reversible semiconductor-metal transition of VO2 thin films synthesized by pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Dumas-Bouchiat, F.; Champeaux, C.; Catherinot, A.; Crunteanu, A.; Blondy, P.

    2007-11-01

    Microwave switching devices based on the semiconductor-metal transition of VO2 thin films were developped on two types of substrates (C-plane sapphire and SiO2/Si), and in both shunt and series configurations. Under thermal activation, the switches achieved up to 30-40dB average isolation of the radio-frequency (rf) signal on 500MHz -35GHz frequency band with weak insertion losses. These VO2-based switches can be electrically activated with commutation times less than 100ns, which make them promising candidates for realizing efficient and simple rf switches.

  4. Estimation of Frequency Noise in Semiconductor Lasers Due to Mechanical Thermal Noise

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2012-01-01

    We evaluate mechanical thermal noise in semiconductor lasers, applying a methodology developed for fixed-spacer cavities for laser frequency stabilization. Our simple model determines an underlying fundamental limit for the frequency noise of free-running semiconductor laser, and provides a framework: where the noise may be potentially reduced with improved design.

  5. Semiconductor-based optical refrigerator

    DOEpatents

    Epstein, Richard I.; Edwards, Bradley C.; Sheik-Bahae, Mansoor

    2002-01-01

    Optical refrigerators using semiconductor material as a cooling medium, with layers of material in close proximity to the cooling medium that carries away heat from the cooling material and preventing radiation trapping. In addition to the use of semiconducting material, the invention can be used with ytterbium-doped glass optical refrigerators.

  6. Comparison of thermal management techniques for semiconductor disk lasers

    NASA Astrophysics Data System (ADS)

    Giet, S.; Kemp, A. J.; Burns, D.; Calvez, S.; Dawson, M. D.; Suomalainen, S.; Harkonen, A.; Guina, M.; Okhotnikov, O.; Pessa, M.

    2008-02-01

    Semiconductor Disk Lasers (SDLs) are compact lasers suitable for watt to multi-watt direct generation in the 670- 2350nm waveband and frequency-doubled operation in the ultraviolet and visible regions. This is, however, critically dependent on the thermal management strategy used as, in this type of laser, the pump is absorbed over micrometer lengths and the gain and loss are temperature sensitive. In this paper, we compare the two heat dissipation techniques that have been successfully deployed to-date: the "thin device" approach where the semiconductor active mirror is bonded onto a heatsink and its substrate subsequently removed, and the "heatspreader" technique where a high thermal conductivity platelet is directly bonded onto the active part of the unprocessed epilayer. We show that for SDLs emitting at 1060nm with pump spots of ~80µm diameter, the heatspreader approach outperforms the thin-device alternative, with the best results being obtained with a diamond heatspreader. Indeed, the thermal resistances are measured to be 4.9, 10.4 and 13.0 K/W for diamond-bonded, SiC-bonded and flip-chip devices respectively. It is also observed, as expected, that the thermal management strategy indirectly affects the optimum output coupling and thus the overall performance of these lasers.

  7. Reliability of high-power semiconductor laser arrays

    NASA Astrophysics Data System (ADS)

    Kung, Hsing H.; Craig, Richard R.; Zucker, Erik P.; Li, Benjamin; Scifres, Donald R.

    1992-10-01

    The reliability of continuously operating (cw) high power laser arrays is a critical factor for the acceptance of these devices in a wide range of applications. Extensive investigation into the reliability of semiconductor lasers has led to an improved understanding of failure mechanisms such as material defects, mirror damage and solder related failures as well as to methods which significantly suppress the occurrence of catastrophic failure. Furthermore, as a result of material quality improvements, laser arrays exhibit very low gradual degradation for high power operation up to 2 Watts cw. Long term lifetest data shows that the projected medium life at room temperature of such devices exceed 100,000 hours at 2 W cw.

  8. Numerical stability maps of an optically injected semiconductor laser

    NASA Astrophysics Data System (ADS)

    Fordell, T.; Lindberg, Å. M.

    2004-12-01

    Detailed experimental mappings of the dynamics of a Fabry-Pérot type semiconductor laser subjected to external optical injection along with parameters describing the injected laser have been published by Eriksson and Lindberg [J. Opt. B: Quantum Semiclass. Opt. 4 (2002) 149] and by Eriksson [Opt. Commun. 210 (2002) 343]. This paper reports on a numerical investigation of the injection experiments. By computing the largest Lyapunov exponent, the chaotic islands, periodic windows and locking ranges are compared in detail with the experimental results for three different operating points of the laser. The numerical results are in good agreement with the experiment once the linewidth enhancement factor is increased from the earlier reported value of 3.9 ± 0.5 to about 6.7. The new value is confirmed by a re-measurement of the linewidth enhancement factor using a current modulation technique.

  9. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1988-01-01

    Slot timing recovery in a direct detection optical PPM communication system can be achieved by processing the photodetector waveform with a nonlinear device whose output forms the input to a phase lock group. The choice of a simple transition detector as the nonlinearity is shown to give satisfactory synchronization performance. The rms phase error of the recovered slot clock and the effect of slot timing jitter on the bit error probability were directly measured. The experimental system consisted of an AlGaAs laser diode (lambda = 834 nm) and a silicon avalanche photodiode (APD) photodetector and used Q=4 PPM signaling operated at a source data rate of 25 megabits/second. The mathematical model developed to characterize system performance is shown to be in good agreement with actual performance measurements. The use of the recovered slot clock in the receiver resulted in no degradation in receiver sensitivity compared to a system with perfect slot timing. The system achieved a bit error probability of 10 to the minus 6 power at received signal energies corresponding to an average of less than 60 detected photons per information bit.

  10. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1987-01-01

    A 25 megabit/sec direct detection optical communication system that used Q=4 PPM signalling was constructed and its performance measured under laboratory conditions. The system used a single-mode AlGaAs laser diode transmitter and low noise silicon avalanche photodiode (APD) photodetector. Comparison of measured performance with the theoretical revealed that modeling the APD output as a Gaussian process under conditions of negligible background radiation and low (less than 10 to the -12 power A) APD bulk leakage currents leads to substantial underestimates of optimal APD gain to use and overestimates of system bit error probability. A procedure is given to numerically compute system performance which uses the more accurate Webb's Approximation of the exact Conradi distribution for the APD ouput signal that does not require excessive amounts of computer time (a few minutes of VAX 8600 CPU time per system operating point). Examples are given which illustrate the breakdown of the Gaussian approximation in assessing system performance. This system achieved a bit error probability of 10 to the -6 power at a received signal energy corresponding to an average of 60 absorbed photons/bit and optimal APD gain of 700.

  11. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation.

    PubMed

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

    2016-07-19

    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems.

  12. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

    NASA Astrophysics Data System (ADS)

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

    2016-07-01

    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems.

  13. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

    PubMed Central

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

    2016-01-01

    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems. PMID:27431769

  14. High-speed modelocked semiconductor lasers and applications in coherent photonic systems

    NASA Astrophysics Data System (ADS)

    Lee, Wangkuen

    1.55-mum high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed (>5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied with respect to the laser linewidth (˜ 3 MHz), the relative intensity noise (RIN) (< -150 dB/Hz), as well as the modal RIN (˜ 3 dB reduction). MSL to MSL, and tunable laser to MSL synchronization is demonstrated by using a dual-mode injection technique and a modulation sideband injection technique, respectively. Dynamic locking behavior and locking bandwidth are experimentally and theoretically studied. Stable laser synchronization between two MSLs is demonstrated with an injection seed power on the order of a few microwatt. Several coherent heterodyne detections based on the synchronized MSL systems are demonstrated for applications in microwave photonic links and ultra-dense wavelength division multiplexing (UD-WDM) system. In addition, efficient coherent homodyne balanced receivers based on synchronized MSLs are developed and demonstrated for a spectrally phase-encoded optical CDMA (SPE-OCDMA) system.

  15. Ultrahigh-power semiconductor lasers and their applications

    NASA Astrophysics Data System (ADS)

    He, Xiaoguang; Srinivasan, Swaminathan T.; Gupta, Shantanu; Patel, Rushikesh M.

    1998-08-01

    High power semiconductor laser diodes have found their place in a wide variety of markets such as printing, pumping of solid state lasers, illumination, medical diagnosis, surgery, spectroscopy and material processing. In the past two years, the performance of the commercial available multi-mode semiconductor laser diodes has been elevated to a ultra high power level (continuous wave (CW) power density higher than 15 mW/micrometers -aperture for single emitter devices and 10 mW/micrometers -aperture per cm wide bar for monolithic arrays) as the result of breakthrough in device design, processing and packaging. We present in this paper record setting performance of these ultra high power devices in terms of CW power (> 10.6 W from 100 micrometers aperture, > 180 W from 1 cm wide array) and efficiency (wall plug-in efficiency 59%, differential quantum efficiency 87%). Reliability tests of these ultra high power devices indicates that these devices have equivalent to or better reliability than conventional lower power commercial devices. We will discuss the significance of these devices in enabling new applications and empowering current applications.

  16. Modeling a semiconductor laser with an intracavity atomic absorber

    SciTech Connect

    Masoller, C.; Vilaseca, R.; Oria, M.

    2009-07-15

    The dynamics of a semiconductor laser with an intracavity atomic absorber is studied numerically. The study is motivated by the experiments of Barbosa et al. [Opt. Lett. 32, 1869 (2007)], using a semiconductor junction as an active medium, with its output face being antireflection coated, and a cell containing cesium vapor placed in a cavity that was closed by a diffraction grating (DG). The DG allowed scanning the lasing frequency across the D{sub 2} line in the Cs spectrum, and different regimes such as frequency bistability or dynamic instability were observed depending on the operating conditions. Here we propose a rate-equation model that takes into account the dispersive losses and the dispersive refractive index change in the laser cavity caused by the presence of the Cs vapor cell. These effects are described through a modification of the complex susceptibility. The numerical results are found to be in qualitative good agreement with some of the observations; however, some discrepancies are also noticed, which can be attributed to multi-longitudinal-mode emission in the experiments. The simulations clearly show the relevant role of the Lamb dips and crossover resonances, which arise on top of the Doppler-broadened D{sub 2} line in the Cs spectrum, and are due to the forward and backward intracavity fields interacting resonantly with the Cs atoms. When the laser frequency is locked in a dip, a reduction in the frequency noise and of the intensity noise is demonstrated.

  17. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation.

    PubMed

    Wan, W J; Li, H; Zhou, T; Cao, J C

    2017-03-08

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification.

  18. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation

    PubMed Central

    Wan, W. J.; Li, H.; Zhou, T.; Cao, J. C.

    2017-01-01

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification. PMID:28272492

  19. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation

    NASA Astrophysics Data System (ADS)

    Wan, W. J.; Li, H.; Zhou, T.; Cao, J. C.

    2017-03-01

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification.

  20. High Efficiency, Room Temperature Mid-Infrared Semiconductor Laser Development for IR Countermeasures

    DTIC Science & Technology

    2009-05-01

    PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) AFOSR/NE 875 N. Randolph St. Rm. 3112 Arlington, VA...through December of 2007, the work was expanded to include the development of plasma etch processes in an Oxford Instruments 100 ICP 180 System for ZnO...characterization and fabrication of antimonide-based semiconductor lasers for infrared applications. The fabrication of the devices continued to be done

  1. Liquid Contact Luminescence from Semiconductor Laser Materials

    DTIC Science & Technology

    1997-01-09

    An important aspect of a solvent’s properties is the protic character (acid-base properties) of the solvent. Protic solvents are strong hydrogen bond ...on the other hand are poor hydrogen bond donors as they generally have hydrogen bound to carbon. They are weakly acidic and pro- ton exchange occurs...20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED 19 Jan 971 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Liquid

  2. Exploring multistability in semiconductor ring lasers: theory and experiment.

    PubMed

    Gelens, L; Beri, S; Van der Sande, G; Mezosi, G; Sorel, M; Danckaert, J; Verschaffelt, G

    2009-05-15

    We report the first experimental observation of multistable states in a single-longitudinal mode semiconductor ring laser. We show how the operation of the device can be steered to either monostable, bistable, or multistable dynamical regimes in a controlled way. We observe that the dynamical regimes are organized in well-reproducible sequences that match the bifurcation diagrams of a two-dimensional model. By analyzing the phase space in this model, we predict how the stochastic transitions between multistable states take place and confirm it experimentally.

  3. An electrically injected rolled-up semiconductor tube laser

    SciTech Connect

    Dastjerdi, M. H. T.; Djavid, M.; Mi, Z.

    2015-01-12

    We have demonstrated electrically injected rolled-up semiconductor tube lasers, which are formed when a coherently strained InGaAs/InGaAsP quantum well heterostructure is selectively released from the underlying InP substrate. The device exhibits strong coherent emission in the wavelength range of ∼1.5 μm. A lasing threshold of ∼1.05 mA is measured for a rolled-up tube with a diameter of ∼5 μm and wall thickness of ∼140 nm at 80 K. The Purcell factor is estimated to be ∼4.3.

  4. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Simple pulsed semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Hulicius, E.; Abrahám, A.; Sĭmeček, T.

    1988-11-01

    A brief review is given of the main characteristics of pulsed GaAlAs/GaAs lasers made in Czechoslovakia. A description is given of laser structures with large optical cavities and their electrical, optical, and service life characteristics are reported.

  5. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Computer model for quasioptic waveguide lasers

    NASA Astrophysics Data System (ADS)

    Wenzel, H.; Wünsche, H. J.

    1988-11-01

    A description is given of a numerical model of a semiconductor laser with a quasioptic waveguide (index guide). This model can be used on a personal computer. The model can be used to find the radiation field distributions in the vertical and lateral directions, the pump currents at the threshold, and also to solve dynamic rate equations.

  6. Compact confocal readout system for three-dimensional memories using a laser-feedback semiconductor laser.

    PubMed

    Nakano, Masaharu; Kawata, Yoshimasa

    2003-08-01

    We present a compact confocal readout system for three-dimensional optical memories that uses the thresholding property of a semiconductor laser for feedback light. The system has higher axial resolution than a conventional confocal system with a pinhole. We demonstrate readout results for data recorded in two recording layers with the developed system.

  7. Slow axis collimation lens with variable curvature radius for semiconductor laser bars

    NASA Astrophysics Data System (ADS)

    Xiong, Ling-Ling; Cai, Lei; Zheng, Yan-Fang; Liu, Hui; Zhang, Pu; Nie, Zhi-Qiang; Liu, Xing-Sheng

    2016-03-01

    Based on Snell's law and the constant phase in the front of optical field, a design method of the slow axis collimation lens with variable curvature radius is proposed for semiconductor laser bars. Variable radius of the collimator is designed by the transmission angle, and it is demonstrated that the collimator has good beam collimation ability by material with low refractive index. Resorting to the design thought of finite element method, the surface of the collimator has been divided, and it is feasible to be fabricated. This method is applied as an example in collimation of a 976 nm semiconductor laser bar. 6 mrad divergence angle of collimated beam at slow axis is realized by the designed collimation lens with refraction index of 1.51.

  8. Imaging of free carriers in semiconductors via optical feedback in terahertz quantum cascade lasers

    SciTech Connect

    Mezzapesa, F. P. Brambilla, M.; Dabbicco, M.; Scamarcio, G.; Columbo, L. L.; Vitiello, M. S.

    2014-01-27

    To monitor the density of photo-generated charge carriers on a semiconductor surface, we demonstrate a detectorless imaging system based on the analysis of the optical feedback in terahertz quantum cascade lasers. Photo-excited free electron carriers are created in high resistivity n-type silicon wafers via low power (≅40 mW/cm{sup 2}) continuous wave pump laser in the near infrared spectral range. A spatial light modulator allows to directly reconfigure and control the photo-patterned intensity and the associated free-carrier density distribution. The experimental results are in good agreement with the numerical simulations.

  9. Optical coherent tomography with electrically tunable semiconductor laser using FMCW techniques

    NASA Astrophysics Data System (ADS)

    Haberland, Udo; Blazek, Vladimir; Schmitt, Hans J.

    1996-12-01

    Imaging of highly scattering objects in scattering media can play an important part in assessing melanoma in human skin. The technique to be presented is based on frequency modulated continuous waves using a coherent tunable semiconductor laser irradiating a Michelson interferometer. The electrically tunable laser is characterized and the procedure to linearize the instantaneous frequency with time is described. The temporal point spread function of dilute milk is measured. Finally the performance of our imaging system is demonstrated on 2D-images of solid scattering phantoms and of an eye of a pig.

  10. Intracavity laser spectroscopy with a semiconductor disk laser-pumped cw Cr{sup 2+} : ZnSe laser

    SciTech Connect

    Kozlovsky, V I; Korostelin, Yu V; Podmar'kov, Yu P; Skasyrsky, Ya K; Frolov, M P; Okhotnikov, O G; Akimov, V A

    2013-09-30

    Absorption spectra of the air have been measured near 2.31 μm using intracavity laser spectroscopy with a semiconductor disk laser-pumped cw Cr{sup 2+} : ZnSe laser. It is shown that, at lasing times of at least 3 ms, the sensitivity of the laser to intracavity absorption increases. This allows one to reach an effective path length of 900 km and enables detection of weak lines with absorption coefficients down to 1 × 10{sup -9} cm{sup -1}. (laser spectroscopy)

  11. Modeling and Simulation of Semiconductor Quantum Well Structures and Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    In this talk I will cover two aspects of modeling and simulation efforts at NASA Ames Research Center. In the quantum well structure simulation, we typically start from the quantum mechanical calculation of the quantum well structures for the confined/and unconfined eigen states and functions. A bandstructure calculation of the k*p type is then performed for the confined valence states. This information is then used to computer the optical gain and refractive index of the quantum well structures by solving the linearized multiband semiconductor Bloch equations with the many-body interactions included. In our laser simulation, we typically solve the envelope equations for the laser field in space-time domain, coupled with a reduced set of material equations using the microscopic calculation of the first step. Finally I will show some examples of both aspects of simulation and modeling.

  12. Nonlinear dynamics of semiconductor lasers with feedback and modulation.

    PubMed

    Toomey, J P; Kane, D M; Lee, M W; Shore, K A

    2010-08-02

    The nonlinear dynamics of two semiconductor laser systems: (i) with optical feedback, and (ii) with optical feedback and direct current modulation are evaluated from multi-GHz-bandwidth output power time-series. Animations of compilations of the RF spectrum (from the FFT of the time-series) as a function of optical feedback level, injection current and modulation signal strength is demonstrated as a new tool to give insight into the dynamics. The results are contrasted with prior art and new observations include fine structure in the RF spectrum at low levels of optical feedback and non-stationary switching between periodic and chaotic dynamics for some sets of laser system parameters. Correlation dimension analysis successfully identifies periodic dynamics but most of the dynamical states are too complex to be extracted using standard algorithms.

  13. From Dye Laser Factory to Portable Semiconductor Laser: Four Generations of Sodium Guide Star Lasers for Adaptive Optics in Astronomy and Space Situational Awareness

    NASA Astrophysics Data System (ADS)

    d'Orgeville, C.; Fetzer, G.

    This presentation recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analysing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980's and 1990's. These experimental systems were turned into the first laser guide star facilities to equip medium-to-large diameter adaptive optics telescopes, opening a new era of LGS AO-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000's that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8-10m class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers will be deployed at two astronomical telescopes and at least one space debris tracking station this year. Although highly promising, these systems remain significantly expensive and they have yet to demonstrate high performance in the field. We are proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide the final solution to the problem of sodium laser guide star adaptive optics for all astronomy and space situational awareness applications.

  14. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Influence of spontaneous fluctuations on the emission spectrum of an injection semiconductor laser

    NASA Astrophysics Data System (ADS)

    Gulyaev, Yurii V.; Suris, Robert A.; Tager, A. A.; Élenkrig, B. B.

    1988-11-01

    A theoretical investigation is made of fluctuation-induced excitation of side longitudinal modes in the emission spectra of semiconductor lasers, including those with an external mirror. It is shown that nonlinear refraction of light in the active region of a semiconductor laser may result in a noise redistribution of the radiation between longitudinal resonator modes and can be responsible for the multimode nature of the average emission spectrum. An analysis is made of the influence of selectivity of an external mirror on the stability of cw operation, minimum line width, and mode composition of the emission spectra of semiconductor lasers. The conditions for maximum narrowing of the emission spectrum of a semiconductor laser with an external selective mirror are identified.

  15. MBE growth and characterization of semiconductor laser coolers

    NASA Astrophysics Data System (ADS)

    Stintz, Andreas; Li, Chia-Yeh; Sheik-Bahae, Mansoor; Malloy, Kevin J.

    2009-02-01

    Laser cooling of a semiconductor has been an elusive but highly desirable goal for several years. Although it is theoretically possible, tedious and often time-consuming sample preparation, processing and testing has slowed the progress on the experimental end. The work presented here focuses on a new approach to the first step, the growth of high quality starting samples by molecular beam epitaxy (MBE). MBE is believed to have an inherent advantage over chemical vapor deposition techniques since typically material with higher purity can be grown by MBE, thereby reducing the chance for parasitic absorption and nonradiative recombinations to occur. Additionally, with MBE very precise control over interfaces is possible, where a significant portion of the non-radiative traps are usually located. The most promising material for laser cooling is the binary compound GaAs. The lattice-matched material Ga0.515In0.485P is chosen for passivating the surface as it has shown much longer radiative lifetimes in GaAs than, for example, AlxGa1-xAs. The present study focuses on growth optimization of Ga0.515In0.485P/GaAs/Ga0.515In0.485P heterostructures and the influence of growth conditions on sample suitability for laser cooling as measured by non-radiative lifetimes in GaAs. In particular, parameters such as growth temperature, group V:III overpressure, substrate orientation, doping, and interface composition on a monolayer length scale are varied and analyzed. The suitability of an optimized sample for semiconductor laser cooling is discussed.

  16. Photoconductive semiconductor switches: Laser Q-switch trigger and switch-trigger laser integration

    SciTech Connect

    Loubriel, G.M.; Mar, A.; Hamil, R.A.; Zutavern, F.J.; Helgeson, W.D.

    1997-12-01

    This report provides a summary of the Pulser In a Chip 9000-Discretionary LDRD. The program began in January of 1997 and concluded in September of 1997. The over-arching goal of this LDRD is to study whether laser diode triggered photoconductive semiconductor switches (PCSS) can be used to activate electro-optic devices such as Q-switches and Pockels cells and to study possible laser diode/switch integration. The PCSS switches we used were high gain GaAs switches because they can be triggered with small amounts of laser light. The specific goals of the LDRD were to demonstrate: (1) that small laser diode arrays that are potential candidates for laser-switch integration will indeed trigger the PCSS switch, and (2) that high gain GaAs switches can be used to trigger optical Q-switches in lasers such as the lasers to be used in the X-1 Advanced Radiation Source and the laser used for direct optical initiation (DOI) of explosives. The technology developed with this LDRD is now the prime candidate for triggering the Q switch in the multiple lasers in the laser trigger system of the X-1 Advanced Radiation Source and may be utilized in other accelerators. As part of the LDRD we developed a commercial supplier. To study laser/switch integration we tested triggering the high gain GaAs switches with: edge emitting laser diodes, vertical cavity surface emitting lasers (VCSELs), and transverse junction stripe (TJS) lasers. The first two types of lasers (edge emitting and VCSELs) did activate the PCSS but are harder to integrate with the PCSS for a compact package. The US lasers, while easier to integrate with the switch, did not trigger the PCSS at the US laser power levels we used. The PCSS was used to activate the Q-switch of the compact laser to be used in the X-1 Advanced Radiation Source.

  17. IV-VI semiconductor lasers for gas phase biomarker detection

    NASA Astrophysics Data System (ADS)

    McCann, Patrick; Namjou, Khosrow; Roller, Chad; McMillen, Gina; Kamat, Pratyuma

    2007-09-01

    A promising absorption spectroscopy application for mid-IR lasers is exhaled breath analysis where sensitive, selective, and speedy measurement of small gas phase biomarker molecules can be used to diagnose disease and monitor therapies. Many molecules such as nitric oxide, ethane, formaldehyde, acetaldehyde, acetone, carbonyl sulfide, and carbon disulfide have been connected to diseases or conditions such as asthma, oxidative stress, breast cancer, lung cancer, diabetes, organ transplant rejection, and schizophrenia. Measuring these and other, yet to be discovered, biomarker molecules in exhaled breath with mid-IR lasers offers great potential for improving health care since such tests are non-invasive, real-time, and do not require expensive consumables or chemical reagents. Motivated by these potential benefits, mid-IR laser spectrometers equipped with presently available cryogenically-cooled IV-VI lasers mounted in compact Stirling coolers have been developed for clinical research applications. This paper will begin with a description of the development of mid-IR laser instruments and their use in the largest known exhaled breath clinical study ever performed. It will then shift to a description of recent work on the development of new IV-VI semiconductor quantum well materials and laser fabrication methods that offer the promise of low power consumption (i.e. efficient) continuous wave emission at room temperature. Taken together, the demonstration of compelling clinical applications with large market opportunities and the clear identification of a viable pathway to develop low cost mid-IR laser instrumentation can create a renewed focus for future research and development efforts within the mid-IR materials and devices area.

  18. Period-control and chaos-anti-control of a semiconductor laser using the twisted fiber

    NASA Astrophysics Data System (ADS)

    Yan, Sen-Lin

    2016-09-01

    A novel semiconductor laser system is presented based on a twisted fiber. To study the period-control and chaos-anti-control of the laser system, we design a type of optic path as a control setup using the combination of the twisted fiber and the polarization controller while we present a physical dynamics model of the delayed dual-feedback laser containing the twisted fiber effect. We give an analysis of the effect of the twisted fiber on the laser. We use the effects of the delayed phase and the rotation angle of the twisted fiber and the characteristics of the system to achieve control of the laser. The laser is deduced to a stable state, a double-periodic state, a period-6 state, a period-8 state, a period-9 state, a multi-period state, beat phenomenon, and so on. The periodic laser can be anti-controlled to chaos. Some chaos-anti-control area is found. The laser system is very useful for the study of chaos-control of the laser setup and the applications of some physics effects.

  19. Pulse repetition rate scaling from 5 to 100 GHz with a high-power semiconductor disk laser.

    PubMed

    Mangold, Mario; Zaugg, Christian A; Link, Sandro M; Golling, Matthias; Tilma, Bauke W; Keller, Ursula

    2014-03-10

    The high-power semiconductor laser studied here is a modelocked integrated external-cavity surface emitting laser (MIXSEL), which combines the gain of vertical-external-cavity surface-emitting lasers (VECSELs) with the saturable absorber of a semiconductor saturable absorber mirror (SESAM) in a single semiconductor layer stack. The MIXSEL concept allows for stable and self-starting fundamental passive modelocking in a simple straight cavity and the average power scaling is based on the semiconductor disk laser concept. Previously record-high average output power from an optically pumped MIXSEL was demonstrated, however the long pulse duration of 17 ps prevented higher pulse repetition rates and many interesting applications such as supercontinuum generation and broadband frequency comb generation. With a novel MIXSEL structure, the first femtosecond operation was then demonstrated just recently. Here we show that such a MIXSEL can also support pulse repetition rate scaling from ≈5 GHz to >100 GHz with excellent beam quality and high average output power, by mechanically changing the cavity length of the linear straight cavity and the output coupler. Up to a pulse repetition rate of 15 GHz we obtained average output power >1 W and pulse durations <4 ps. Furthermore we have been able to demonstrate the highest pulse repetition rate from any fundamentally modelocked semiconductor disk laser with 101.2 GHz at an average output power of 127 mW and a pulse duration of 570 fs.

  20. Intermediate high index layer for laser mode tuning in organic semiconductor lasers.

    PubMed

    Stroisch, M; Woggon, T; Teiwes-Morin, C; Klinkhammer, S; Forberich, K; Gombert, A; Gerken, M; Lemmer, U

    2010-03-15

    We modified the optical properties of organic semiconductor distributed feedback lasers by introducing a high refractive index layer consisting of tantalum pentoxide between the substrate and the active material layer. A thin film of tris-(8-hydroxyquinoline) aluminium doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran was used as the active layer. By varying the intermediate layer thickness we could change the effective refractive index of the guided laser mode and thus the laser wavelength. With this technique we were able to tune the laser emission range between 613 nm and 667 nm. For high index layer thicknesses higher than 40 nm the laser operated on the TE(1)-mode rather than the fundamental TE(0)-mode.

  1. Processing and packaging of semiconductor lasers and optoelectronic devices; Proceedings of the Meeting, Los Angeles, CA, Jan. 20, 21, 1993

    NASA Astrophysics Data System (ADS)

    Temkin, Henryk

    1993-06-01

    Various papers on processing and packaging of semiconductor laser and optoelectronic devices are presented. Individual topics addressed include: buried heterostructure lasers based on InGaAsP/InP, fabrication processes for GaAs-based high-power diode lasers, fast and reliable processing of high-performance InGaAs 0.98 micron laser diodes, 1.3 micron InGaAsP/InP buried-crescent lasers with narrow spread of threshold currents, Si-based laser subassembly for telecommunications, inexpensive packaging techniques of fiber pigtailed laser diodes, high-performance packaging of gigabit data communication optical modules, applications of diamond made by chemical-vapor deposition for semiconductor laser submounts. Also discussed are: packaging of optical interconnect arrays for optical signal processing and computing, coupling 4 W cw from a diode-pumped Nd:YAG laser through a 5-micron-core single-mode fiber, microoptic and microelectronic infrared packaging of vertical-cavity laser arrays, vertical-cavity surface-emitting laser technology, direct contact-type image sensor unit.

  2. Determination of nanovibration amplitudes using frequency-modulated semiconductor laser autodyne

    SciTech Connect

    Usanov, D A; Skripal, A V; Astakhov, E I

    2014-02-28

    The method for measuring nanovibration amplitudes using the autodyne signal of a semiconductor laser at several laser radiation wavelengths is described. The theoretical description of the frequency-modulated autodyne signal under harmonic vibrations of the reflector is presented and the relations for its spectral components are derived using the expansions into the Fourier and Bessel series. The results of numerical modelling based on the proposed method for measuring the reflector nanovibration amplitudes are presented that make use of the low-frequency spectrum of the autodyne signal from the frequency-modulated laser autodyne and the solution of the appropriate inverse problem. The experimental setup is described; the results of the measurements are presented for the nanovibration amplitudes and the autodyne signal spectra under the reflector nanovibrations. (laser applications and other topics in quantum electronics)

  3. All-electronic line width reduction in a semiconductor diode laser using a crystalline microresonator

    NASA Astrophysics Data System (ADS)

    Rury, Aaron S.; Mansour, Kamjou; Yu, Nan

    2015-07-01

    This study examines the capability to significantly suppress the frequency noise of a semiconductor distributed feedback diode laser using a universally applicable approach: a combination of a high-Q crystalline whispering gallery mode microresonator reference and the Pound-Drever-Hall locking scheme using an all-electronic servo loop. An out-of-loop delayed self-heterodyne measurement system demonstrates the ability of this approach to reduce a test laser's absolute line width by nearly a factor of 100. In addition, in-loop characterization of the laser stabilized using this method demonstrates a 1-kHz residual line width with reference to the resonator frequency. Based on these results, we propose that utilization of an all-electronic loop combined with the use of the wide transparency window of crystalline materials enable this approach to be readily applicable to diode lasers emitting in other regions of the electromagnetic spectrum, especially in the UV and mid-IR.

  4. Effective observation of treatment of chronic pharyngitis with semiconductor laser irradiation at acupuncture points

    NASA Astrophysics Data System (ADS)

    Li, Suxian; Wang, Xiaoyan; Wang, Yanrong

    1993-03-01

    The treatment of this disease with laser such as He-Ne laser, Nd:YAG laser, and CO2 laser, etc., has been applied in our country, but application of the semiconductor laser therapy has received few reports. It has many advantages, such as ting volume, steady function, simple operation (the patient can operate it by himself), no side effects, remarkable results, and it is very convenient. So the semiconductor laser can be used to treat the chronic pharyngitis with irradiation on acupunctural points. One-hundred-twenty chronic pharyngitis patients were divided into 2 groups, a laser group and a medicine group, 60 cases for each. The effective rate is 91.6% and 66.6%, respectively. Obviously the treatment of chronic pharyngitis with semiconductor laser is valuable for widespread use. The principle of the laser therapy is discussed in the last part of this paper.

  5. Transient gain analysis of gain-switched semiconductor lasers during pulse lasing.

    PubMed

    Chen, Shaoqiang; Ito, Takashi; Asahara, Akifumi; Nakamae, Hidekazu; Nakamura, Takahiro; Yoshita, Masahiro; Kim, Changsu; Zhang, Baoping; Yokoyama, Hiroyuki; Suemoto, Tohru; Akiyama, Hidefumi

    2015-12-10

    We analyzed the transient gain properties of three gain-switched semiconductor lasers with different materials and cavity structures during pulse lasing. All the semiconductor lasers were pumped with impulse optical pumping, and all the generated gain-switched output pulses were well described by exponential functions in their rise parts, wherein the transient gains were derived according to the rate-equation theoretical model. In spite of the different laser structures and materials, the results consistently demonstrated that a higher transient gain produces shorter output pulses, indicating the dominant role of higher transient gain in the generation of even shorter gain-switched pulses with semiconductor lasers.

  6. Numerical simulation of a novel all-optical flip-flop based on a chirped nonlinear distributed feedback semiconductor laser structure using GPGPU computing

    NASA Astrophysics Data System (ADS)

    Zoweil, H.

    2015-05-01

    A novel all-optical flip-flop based on a chirped nonlinear distributed feedback laser structure is proposed. The flip-flop does not require a holding beam. The optical gain is provided by a current injection into an active layer. The nonlinear wave-guiding layer consists of a chirped phase shifted grating accompanied with a negative nonlinear refractive index coefficient that increases in magnitude along the wave-guide. In the 'OFF' state, the chirped grating does not provide the required optical feedback to start lasing. An optical pulse switches the device 'ON' by reducing the chirp due to the negative nonlinear refractive index coefficient. The reduced chirp grating provides enough feedback to sustain a laser mode. The device is switched 'OFF' by cross gain modulation. GPGPU computing allows for long simulation time of multiple SET-RESET operations. The 'ON/OFF' transitions delays are in nanoseconds time scale.

  7. Semiconductor Laser Line-width Measurements for Space Interferometry Applications

    NASA Technical Reports Server (NTRS)

    Dougherty, D.; Guttierrez, R.; Dubovitsky, S.; Forouhar, S.

    1999-01-01

    This work discusses results using the self-heterodyne delay atechnique to measure 1.3 um InP based DFB lasers. We will also address practical issues concerning detection and elimination of back reflections, choice of fiber length and resolution, and measurement of laser 1/f and current supply noise.

  8. Optically induced transport through semiconductor-based molecular electronics

    NASA Astrophysics Data System (ADS)

    Li, Guangqi; Fainberg, Boris D.; Seideman, Tamar

    2015-04-01

    A tight binding model is used to investigate photoinduced tunneling current through a molecular bridge coupled to two semiconductor electrodes. A quantum master equation is developed within a non-Markovian theory based on second-order perturbation theory with respect to the molecule-semiconductor electrode coupling. The spectral functions are generated using a one dimensional alternating bond model, and the coupling between the molecule and the electrodes is expressed through a corresponding correlation function. Since the molecular bridge orbitals are inside the bandgap between the conduction and valence bands, charge carrier tunneling is inhibited in the dark. Subject to the dipole interaction with the laser field, virtual molecular states are generated via the absorption and emission of photons, and new tunneling channels open. Interesting phenomena arising from memory are noted. Such a phenomenon could serve as a switch.

  9. Optically induced transport through semiconductor-based molecular electronics

    SciTech Connect

    Li, Guangqi; Seideman, Tamar; Fainberg, Boris D.

    2015-04-21

    A tight binding model is used to investigate photoinduced tunneling current through a molecular bridge coupled to two semiconductor electrodes. A quantum master equation is developed within a non-Markovian theory based on second-order perturbation theory with respect to the molecule-semiconductor electrode coupling. The spectral functions are generated using a one dimensional alternating bond model, and the coupling between the molecule and the electrodes is expressed through a corresponding correlation function. Since the molecular bridge orbitals are inside the bandgap between the conduction and valence bands, charge carrier tunneling is inhibited in the dark. Subject to the dipole interaction with the laser field, virtual molecular states are generated via the absorption and emission of photons, and new tunneling channels open. Interesting phenomena arising from memory are noted. Such a phenomenon could serve as a switch.

  10. Advanced excimer laser technologies enable green semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Fukuda, Hitomi; Yoo, Youngsun; Minegishi, Yuji; Hisanaga, Naoto; Enami, Tatsuo

    2014-03-01

    "Green" has fast become an important and pervasive topic throughout many industries worldwide. Many companies, especially in the manufacturing industries, have taken steps to integrate green initiatives into their high-level corporate strategies. Governments have also been active in implementing various initiatives designed to increase corporate responsibility and accountability towards environmental issues. In the semiconductor manufacturing industry, there are growing concerns over future environmental impact as enormous fabs expand and new generation of equipments become larger and more powerful. To address these concerns, Gigaphoton has implemented various green initiatives for many years under the EcoPhoton™ program. The objective of this program is to drive innovations in technology and services that enable manufacturers to significantly reduce both the financial and environmental "green cost" of laser operations in high-volume manufacturing environment (HVM) - primarily focusing on electricity, gas and heat management costs. One example of such innovation is Gigaphoton's Injection-Lock system, which reduces electricity and gas utilization costs of the laser by up to 50%. Furthermore, to support the industry's transition from 300mm to the next generation 450mm wafers, technologies are being developed to create lasers that offer double the output power from 60W to 120W, but reducing electricity and gas consumption by another 50%. This means that the efficiency of lasers can be improve by up to 4 times in 450mm wafer production environments. Other future innovations include the introduction of totally Heliumfree Excimer lasers that utilize Nitrogen gas as its replacement for optical module purging. This paper discusses these and other innovations by Gigaphoton to enable green manufacturing.

  11. Squeezed photon-number noise and sub-Poissonian electrical partition noise in a semiconductor laser

    NASA Technical Reports Server (NTRS)

    Richardson, W. H.; Machida, S.; Yamamoto, Y.

    1991-01-01

    Amplitude noise on the light from a semiconductor laser produced a photocurrent fluctuation spectrum that was a maximum of 85 percent (-8.3 dB) below the shot-noise limit. Squeezing in semiconductor lasers is not limited by the overall quantum, or current transfer, efficiency from the laser injection current to the detector photocurrent. Current leakage away from the lasing junction does not introduce Poissonian partition noise.

  12. 1.56 µm 1 watt single frequency semiconductor disk laser.

    PubMed

    Rantamäki, Antti; Rautiainen, Jussi; Sirbu, Alexei; Mereuta, Alexandru; Kapon, Eli; Okhotnikov, Oleg G

    2013-01-28

    A single frequency wafer-fused semiconductor disk laser at 1.56 µm with 1 watt of output power and a coherence length over 5 km in fiber is demonstrated. The result represents the highest output power reported for a narrow-line semiconductor disk laser operating at this spectral range. The study shows the promising potential of the wafer fusion technique for power scaling of single frequency vertical-cavity lasers emitting in the 1.3-1.6 µm range.

  13. High power semiconductor laser source for space applications

    NASA Astrophysics Data System (ADS)

    Goodwin, A. R.; Whiteaway, J. E. A.; Collar, A. J.

    1986-07-01

    Semiconductor laser sources for optical communication links between geostationary and low Earth orbiting satellites were investigated. Phase locked arrays of coupled stripes or related devices offer single mode operation at much lower optical and current density than other techniques. The highest powers are expected using GaAlAs, the best reliability using InGaAsP. Use of very thin highly doped p-InP buffer layers in planar growth, wide mesas, long cavities, and facet coating for DCPBH lasers are suggested. Continuous output power values up to 340 mW can be generated by unoptimized multimode InGaAsP lasers emitting at 1.3 microns. It should be possible to generate continuous power levels greater than 1000 mW by optimizing facet reflectivity and thermal impedance. The Y-coupled array is the most promising concept. The addition of flared output guides, and the positioning of the couplers close to the facet with the larger number of emitters, should improve performance.

  14. Semiconductor laser asymmetry cutting glass with laser induced thermal-crack propagation

    NASA Astrophysics Data System (ADS)

    Zhao, Chunyang; Zhang, Hongzhi; Wang, Yang

    2014-12-01

    Laser induced thermal-crack propagation (LITP) makes the material to produce an uneven temperature field, maximum temperature can't soften or melt the material, induces the thermal stress, then the crack separates along the cutting path. One of the problems in laser asymmetry cutting glass with LITP is the cutting deviation along scanning trajectory. This study lays great emphasis on considering the dynamic extension of crack to explain the reason of the cutting deviation in laser asymmetry cutting glass, includes asymmetric linear cutting and a quarter of a circular curve cutting. This paper indicates the experiments of semiconductor laser asymmetry cutting glass with LITP. Optical microscope photographs of the glass sheet are obtained to examine the cutting deviation. The extended finite element method (XFEM) is used to simulate the dynamic propagation of crack; the crack path does not have to be specified a priori. The cutting deviation mechanism and the crack propagation process are studied by the stress fields using finite element software ABAQUS. This work provides a theoretical basis to investigate the cutting deviation in laser asymmetry cutting glass. In semiconductor laser asymmetry cutting glass, the tensile stress is the basis of crack propagation, then the compressive stress not only makes the crack to extend stably, but also controls the direction of crack propagation.

  15. Significant increase in wavelength, power, and temperature operating envelopes for semiconductor laser diode bars for solid-state lasers

    NASA Astrophysics Data System (ADS)

    Haden, J.; Plano, B.; Major, J.; Harnagel, G.; Endriz, J.

    Attention is given to the substantial increase in the performance envelope of AlGaAs base semiconductor laser diode array bars (QCW bars) that are available to designers of diode pumped solid-state lasers. Reliable QCW bar performance includes operation to 100 W/cm with greater than 10 exp 9 pulse life, 65 C operation, and 780 to 980 nm wavelength availability (60 W/cm). Consideration is also given to 247-W QCW operation. At Nd:YAG, YLF wavelengths (798-807 nm), significant improvements have been achieved in allowable operating temperature (to 65 C) and operating power (to 100 W). These improvements offer the opportunity for the design of high-efficiency solid-state laser systems that need to operate in relatively severe environments.

  16. Photoconductive Semiconductor Switch Technology for Short Pulse Electromagnetics and Lasers

    SciTech Connect

    Denison, Gary J.; Helgeson, Wesley D.; Hjalmarson, Harold P.; Loubriel, Guillermo M.; Mar, Alan; O'Malley, Martin W.; Zutavern, Fred J.

    1999-08-05

    High gain photoconductive semiconductor switches (PCSS) are being used to produce high power electromagnetic pulses foc (1) compact, repetitive accelerators, (2) ultra-wide band impulse sources, (3) precision gas switch triggers, (4) optically-activated firesets, and (5) high power optical pulse generation and control. High power, sub-nanosecond optical pulses are used for active optical sensors such as compact optical radars and range-gated hallistic imaging systems. Following a brief introduction to high gain PCSS and its general applications, this paper will focus on PCSS for optical pulse generation and control. PCSS technology can be employed in three distinct approaches to optical pulse generation and control: (1) short pulse carrier injection to induce gain-switching in semiconductor lasers, (2) electro-optical Q-switching, and (3) optically activated Q-switching. The most significant PCSS issues for these applications are switch rise time, jitter, and longevity. This paper will describe both the requirements of these applications and the most recent results from PCSS technology. Experiments to understand and expand the limitations of high gain PCSS will also be described.

  17. Solitary and coupled semiconductor ring lasers as optical spiking neurons.

    PubMed

    Coomans, W; Gelens, L; Beri, S; Danckaert, J; Van der Sande, G

    2011-09-01

    We theoretically investigate the possibility of generating pulses in an excitable (asymmetric) semiconductor ring laser (SRL) using optical trigger pulses. We show that the phase difference between the injected field and the electric field inside the SRL determines the direction of the perturbation in phase space. Due to the folded shape of the excitability threshold, this has an important influence on the ability to cross it. A mechanism for exciting multiple consecutive pulses using a single trigger pulse (i.e., multipulse excitability) is revealed. We furthermore investigate the possibility of using asymmetric SRLs in a coupled configuration, which is a first step toward an all-optical neural network using SRLs as building blocks.

  18. Solitary and coupled semiconductor ring lasers as optical spiking neurons

    NASA Astrophysics Data System (ADS)

    Coomans, W.; Gelens, L.; Beri, S.; Danckaert, J.; van der Sande, G.

    2011-09-01

    We theoretically investigate the possibility of generating pulses in an excitable (asymmetric) semiconductor ring laser (SRL) using optical trigger pulses. We show that the phase difference between the injected field and the electric field inside the SRL determines the direction of the perturbation in phase space. Due to the folded shape of the excitability threshold, this has an important influence on the ability to cross it. A mechanism for exciting multiple consecutive pulses using a single trigger pulse (i.e., multipulse excitability) is revealed. We furthermore investigate the possibility of using asymmetric SRLs in a coupled configuration, which is a first step toward an all-optical neural network using SRLs as building blocks.

  19. Purcell effect in sub-wavelength semiconductor lasers.

    PubMed

    Gu, Qing; Slutsky, Boris; Vallini, Felipe; Smalley, Joseph S T; Nezhad, Maziar P; Frateschi, Newton C; Fainman, Yeshaiahu

    2013-07-01

    We present a formal treatment of the modification of spontaneous emission rate by a cavity (Purcell effect) in sub-wavelength semiconductor lasers. To explicitly express the assumptions upon which our formalism builds, we summarize the results of non-relativistic quantum electrodynamics (QED) and the emitter-field-reservoir model in the quantum theory of damping. Within this model, the emitter-field interaction is modified to the extent that the field mode is modified by its environment. We show that the Purcell factor expressions frequently encountered in the literature are recovered only in the hypothetical condition when the gain medium is replaced by a transparent medium. Further, we argue that to accurately evaluate the Purcell effect, both the passive cavity boundary and the collective effect of all emitters must be included as part of the mode environment.

  20. Spatial and Spectral Brightness Enhancement of High Power Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Leidner, Jordan Palmer

    The performance of high-power broad-area diode lasers is inhibited by beam filamentation induced by free-carrier-based self-focusing. The resulting beam degradation limits their usage in high-brightness, high-power applications such as pumping fiber lasers, and laser cutting, welding, or marking. Finite-difference propagation method simulations via RSoft's BeamPROP commercial simulation suite and a custom-built MATLAB code were used for the study and design of laser cavities that suppress or avoid filamentation. BeamPROP was used to design a tapered, passive, multi-mode interference cavity for the creation of a self-phase-locking laser array, which is comprised of many single-mode gain elements coupled to a wide output coupler to avoid damage from local high optical intensities. MATLAB simulations were used to study the effects of longitudinal and lateral cavity confinement on lateral beam quality in conventional broad-area lasers. This simulation was expanded to design a laser with lateral gain and index prescription that is predicted to operate at or above state-of-the-art powers while being efficiently coupled to conventional telecom single-mode optical fibers. Experimentally, a commercial broad-area laser was coupled in the far-field to a single-mode fiber Bragg grating to provide grating-stabilized single-mode laser feedback resulting in measured spectral narrowing for efficient pump absorption. Additionally a 19 GHz-span, spatially resolved, self-heterodyne measurement was made of a broad-area laser to study the evolution/devolution of the mode content of the emitted laser beam with increasing power levels.

  1. Improved low-power semiconductor diode lasers for photodynamic therapy in veterinary medicine

    NASA Astrophysics Data System (ADS)

    Lee, Susanne M.; Mueller, Eduard K.; Van de Workeen, Brian C.; Mueller, Otward M.

    2001-05-01

    Cryogenically cooling semiconductor diode lasers provides higher power output, longer device lifetime, and greater monochromaticity. While these effects are well known, such improvements have not been quantified, and thus cryogenically operated semiconductor lasers have not been utilized in photodynamic therapy (PDT). We report quantification of these results from laser power meter and photospectrometer data. The emission wavelengths of these low power multiple quantum well semiconductor lasers were found to decrease and become more monochromatic with decreasing temperature. Significant power output improvements also were obtained at cryogenic temperatures. In addition, the threshold current, i.e. the current at which lasing begins, decreased with decreasing temperature. This lower threshold current combined with the increased power output produced dramatically higher device efficiencies. It is proposed that cryogenic operation of semiconductor diode lasers will reduce the number of devices needed to produce the requisite output for many veterinary and medical applications, permitting significant cost reductions.

  2. Fundamental Limit of 1/f Frequency Noise in Semiconductor Lasers Due to Mechanical Thermal Noise

    NASA Technical Reports Server (NTRS)

    Numata, K.; Camp, J.

    2011-01-01

    So-called 1/f noise has power spectral density inversely proportional to frequency, and is observed in many physical processes. Single longitudinal-mode semiconductor lasers, used in variety of interferometric sensing applications, as well as coherent communications, exhibit 1/f frequency noise at low frequency (typically below 100kHz). Here we evaluate mechanical thermal noise due to mechanical dissipation in semiconductor laser components and give a plausible explanation for the widely-observed 1/f frequency noise, applying a methodology developed for fixed-spacer cavities for laser frequency stabilization. Semiconductor-laser's short cavity, small beam radius, and lossy components are expected to emphasize thermal-noise-limited frequency noise. Our simple model largely explains the different 1/f noise levels observed in various semiconductor lasers, and provides a framework where the noise may be reduced with proper design.

  3. Apparatus For Linewidth Reduction in Distributed Feedback or Distributed Bragg Reflector Semiconductor Lasers Using Vertical Emission

    NASA Technical Reports Server (NTRS)

    Cook, Anthony L. (Inventor); Hendricks, Herbert D. (Inventor)

    2000-01-01

    The linewidth of a distributed feedback semiconductor laser or a distributed Bragg reflector laser having one or more second order gratings is reduced by using an external cavity to couple the vertical emission back into the laser. This method and device prevent disturbance of the main laser beam, provide unobstructed access to laser emission for the formation of the external cavity, and do not require a very narrow heat sink. Any distributed Bragg reflector semiconductor laser or distributed feedback semiconductor laser that can produce a vertical emission through the epitaxial material and through a window in the top metallization can be used. The external cavity can be formed with an optical fiber or with a lens and a mirror or grating.

  4. 1 W at 785 nm from a frequency-doubled wafer-fused semiconductor disk laser.

    PubMed

    Rantamäki, Antti; Rautiainen, Jussi; Lyytikäinen, Jari; Sirbu, Alexei; Mereuta, Alexandru; Kapon, Eli; Okhotnikov, Oleg G

    2012-04-09

    We demonstrate an optically pumped semiconductor disk laser operating at 1580 nm with 4.6 W of output power, which represents the highest output power reported from this type of laser. 1 W of output power at 785 nm with nearly diffraction-limited beam has been achieved from this laser through intracavity frequency doubling, which offers an attractive alternative to Ti:sapphire lasers and laser diodes in a number of applications, e.g., in spectroscopy, atomic cooling and biophotonics.

  5. Modeling and cavity optimization of an external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Feies, Valentin I.; Montrosset, Ivo

    2004-09-01

    Semiconductor external cavity lasers (ECL) have a wide range of applications in the field of DWDM and measurement systems. One of their most important features is the continuous tuning without mode hopping in a wide wavelength range. In this paper we present a modelling approach for an ECL in Littman-Metcalf configuration carried out for optimising: 1) the laser diode position inside the cavity in order to maximize the range of continuous wavelength tuning without mode hopping and without cavity-length adjustment and 2) the choice of the detuning of the operating wavelength respect to the Bragg condition in order to minimize the four-wave mixing (FWM) effects and the effect of a non-perfect antireflection coating (ARC). A realistic example has been analyzed and therefore we considered: the wavelength dependence of the modal gain, linewidth enhancement factor and grating selectivity, as well as the modal refractive index change with carrier injection, operating wavelength and temperature. The implemented numerical tools allow also to obtain some specifications on the grating selectivity and the ARC design.

  6. Two-Photon-Pumped Perovskite Semiconductor Nanocrystal Lasers.

    PubMed

    Xu, Yanqing; Chen, Qi; Zhang, Chunfeng; Wang, Rui; Wu, Hua; Zhang, Xiaoyu; Xing, Guichuan; Yu, William W; Wang, Xiaoyong; Zhang, Yu; Xiao, Min

    2016-03-23

    Two-photon-pumped lasers have been regarded as a promising strategy to achieve frequency up-conversion for situations where the condition of phase matching required by conventional approaches cannot be fulfilled. However, their practical applications have been hindered by the lack of materials holding both efficient two-photon absorption and ease of achieving population inversion. Here, we show that this challenge can be tackled by employing colloidal nanocrystals of perovskite semiconductors. We observe highly efficient two-photon absorption (with a cross section of 2.7 × 10(6) GM) in toluene solutions of CsPbBr3 nanocrystals that can excite large optical gain (>500 cm(-1)) in thin films. We have succeeded in demonstrating stable two-photon-pumped lasing at a remarkable low threshold by coupling CsPbBr3 nanocrystals with microtubule resonators. Our findings suggest perovskite nanocrystals can be used as excellent gain medium for high-performance frequency-up-conversion lasers toward practical applications.

  7. Content-Based Image Retrieval for Semiconductor Process Characterization

    NASA Astrophysics Data System (ADS)

    Tobin, Kenneth W.; Karnowski, Thomas P.; Arrowood, Lloyd F.; Ferrell, Regina K.; Goddard, James S.; Lakhani, Fred

    2002-12-01

    Image data management in the semiconductor manufacturing environment is becoming more problematic as the size of silicon wafers continues to increase, while the dimension of critical features continues to shrink. Fabricators rely on a growing host of image-generating inspection tools to monitor complex device manufacturing processes. These inspection tools include optical and laser scattering microscopy, confocal microscopy, scanning electron microscopy, and atomic force microscopy. The number of images that are being generated are on the order of 20,000 to 30,000 each week in some fabrication facilities today. Manufacturers currently maintain on the order of 500,000 images in their data management systems for extended periods of time. Gleaning the historical value from these large image repositories for yield improvement is difficult to accomplish using the standard database methods currently associated with these data sets (e.g., performing queries based on time and date, lot numbers, wafer identification numbers, etc.). Researchers at the Oak Ridge National Laboratory have developed and tested a content-based image retrieval technology that is specific to manufacturing environments. In this paper, we describe the feature representation of semiconductor defect images along with methods of indexing and retrieval, and results from initial field-testing in the semiconductor manufacturing environment.

  8. Merged beam laser design for reduction of gain-saturation and two-photon absorption in high power single mode semiconductor lasers.

    PubMed

    Lysevych, M; Tan, H H; Karouta, F; Fu, L; Jagadish, C

    2013-04-08

    In this paper we report a method to overcome the limitations of gain-saturation and two-photon absorption faced by developers of high power single mode InP-based lasers and semiconductor optical amplifiers (SOA) including those based on wide-waveguide or slab-coupled optical waveguide laser (SCOWL) technology. The method is based on Y-coupling design of the laser cavity. The reduction in gain-saturation and two-photon absorption in the merged beam laser structures (MBL) are obtained by reducing the intensity of electromagnetic field in the laser cavity. Standard ridge-waveguide lasers and MBLs were fabricated, tested and compared. Despite a slightly higher threshold current, the reduced gain-saturation in MBLs results in higher output power. The MBLs also produced a single spatial mode, as well as a strongly dominating single spectral mode which is the inherent feature of MBL-type cavity.

  9. Excimer laser induced diffusion in magnetic semiconductor quantum wells

    NASA Astrophysics Data System (ADS)

    Howari, H.; Sands, D.; Nicholls, J. E.; Hogg, J. H. C.; Stirner, T.; Hagston, W. E.

    2000-08-01

    Studies of pulsed laser annealing (PLA) of CdTe/CdMnTe quantum well structures are made in order to examine depth dependent effects in laser irradiated semiconductors. Since diffusion coefficients are strongly dependent on the temperature, depth resolution is achieved because the diffusion of Mn from the barriers into the quantum wells is depth dependent. Multiple quantum well (MQW) structures of CdTe/CdMnTe were annealed with single pulses from an XeCl laser at 308 nm. At a threshold of 90 mJ cm-2 two new emission bands are observed that are attributed to the diffusion of Mn from barrier layers to QWs. The diffusion associated with these bands, measured as the integrated product of the diffusion constant and time, is found to be 300 and 30 Å2. Calculations of the temperature, reached within the surface following PLA, using an analytical solution of the heat diffusion equation coupled with known high temperature diffusion coefficients predict the diffusion to decrease by one order of magnitude within one period at the top of the MQW stack. It is suggested that at the threshold surface melting occurs and that these emission bands arise from the QWs immediately beneath the melt front. The diffusion of Mn ions into the QWs is confirmed by magneto-optical data. A further emission band occurs at this same threshold with a Mn concentration above that of the concentration in the barrier layers of the MQW stack. This emission is attributed tentatively to the segregation of the Mn ion within the molten region following recrystallization.

  10. Compact ultrafast semiconductor disk laser for nonlinear imaging in living organisms

    NASA Astrophysics Data System (ADS)

    Aviles-Espinosa, Rodrigo; Filippidis, G.; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J.; Südmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Artigas, David; Loza-Alvarez, Pablo

    2011-03-01

    Ultrashort pulsed laser systems (such as Ti:sapphire) have been used in nonlinear microscopy during the last years. However, its implementation is not straight forward as they are maintenance-intensive, bulky and expensive. These limitations have prevented their wide-spread use for nonlinear imaging, especially in "real-life" biomedical applications. In this work we present the suitability of a compact ultrafast semiconductor disk laser source, with a footprint of 140x240x70 mm, to be used for nonlinear microscopy. The modelocking mechanism of the laser is based on a quantumdot semiconductor saturable absorber mirror (SESAM). The laser delivers an average output power of 287 mW with 1.5 ps pulses at 500 MHz, corresponding to a peak power of 0.4 kW. Its center wavelength is 965 nm which is ideally suited for two-photon excitation of the widely used Green Fluorescent Protein (GFP) marker as it virtually matches its twophoton action cross section. We reveal that it is possible to obtain two photon excited fluorescence images of GFP labeled neurons and secondharmonic generation images of pharynx and body wall muscles in living C. elegans nematodes. Our results demonstrate that this compact laser is well suited for long-term time-lapse imaging of living samples as very low powers provide a bright signal. Importantly this non expensive, turn-key, compact laser system could be used as a platform to develop portable nonlinear bio-imaging devices, facilitating its wide-spread adoption in "real-life" applications.

  11. Ultrafast switching based on field optical bistability in nano-film of semiconductor

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Egorenkov, Vladimir A.; Loginova, Maria M.

    2016-09-01

    Using computer simulation, we show a possibility of ultrafast switching between stable states of an optical bistable device based on nano-film of semiconductor. Optical bistability occurs because of nonlinear dependence of semiconductor absorption coefficient on electric field potential. Electric field is induced by a laser pulse due to charged particles generation. The main feature of this bistable element is low absorption energy, which is necessary for switching, in comparison with bistable element based on other physical mechanism of laser energy absorption. For computer simulation of a problem under consideration a new finite-difference scheme is proposed using the original iterative process.

  12. Toward High Performance Integrated Semiconductor Micro and Nano Lasers Enabled by Transparent Conducting Materials: from Thick Structure to Thin Film

    NASA Astrophysics Data System (ADS)

    Ou, Fang

    Integrated semiconductor lasers working at the wavelength around 1.3 microm and 1.55 microm are of great interest for the research of photonic integrated circuit (PIC) since they are the crucial components for optical communications and many other applications. To satisfy the requirement of the next generation optical communication and computing systems, integrated semiconductor lasers are expected to have high device performance like very low lasing threshold, high output powers, high speed and possibility of being integrated with electronics. This dissertation focuses on the design and realization of InP based high performance electrically pumped integrated semiconductor lasers. In the dissertation, we first design the tall structure based electrically pumped integrated micro-lasers. Those lasers are capable of giving >10 mW output power with a moderate low threshold current density (0.5--5 kA/cm 2). Besides, a new enhanced radiation loss based coupler design is demonstrated to realize single directional output for curvilinear cavities. Second, the thin film structure based integrated semiconductor laser designs are proposed. Both structures use the side conduction geometry to enable the electrical injection into the thin film laser cavity. The performance enhancement of the thin film structure based lasers is analyzed compared to the tall structure. Third, we investigate the TCO materials. CdO deposited by PLD and In 2O3 deposited by IAD are studied from aspects of their physical, optical and electrical properties. Those materials can give a wide range of tunability in their conductivity (1--5000 S/cm) and optical transparency (loss 200--5000 cm-1), which is of great interest in realizing novel nanophotonic devices. In addition, the electrical contact properties of those materials to InP are also studied. Experiment result shows that both CdO and In2O3 can achieve good ohmic contact to n-InP with contact resistance as low as 10-6O·cm 2. At last, we investigate

  13. High-power semiconductor lasers at eye-safe wavelengths

    NASA Astrophysics Data System (ADS)

    Osowski, Mark L.; Gewirtz, Yossi; Lammert, Robert M.; Oh, Se W.; Panja, Chameli; Elarde, Victor C.; Vaissie, Laurent; Patel, Falgun D.; Ungar, Jeffrey E.

    2009-05-01

    InP based diode lasers are required to realize the next generation of eyesafe applications, including direct rangefinding and HEL weapons systems. We report on the progress of high power eyesafe single spatial and longitudinal mode 1550nm MOPA devices, where we have achieved peak powers in excess of 10W with 50ns pulse widths. A conceptual model based on our recent MOPA results show the path towards scaling to high powers based on spatial beam combination with operating conditions suitable for direct rangefinding applications. We also report on the progress towards high power 14xx and 15xx nm pump lasers for eyesafe HEL systems.

  14. Highly efficient neodymium:yttrium aluminum garnet laser end pumped by a semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Sipes, D. L.

    1985-01-01

    In recent experiments, 80-mW CW power in a single mode has been achieved from a neodymium:yttrium aluminum garnet (Nd:YAG) laser with only 1 W of electrical power input to a single semiconductor laser array pump. This corresponds to an overall efficiency of 8 percent, the highest reported CW efficiency for a Nd:YAG laser. A tightly focused semiconductor laser end pump configuration is used to achieve high pumping intensities (on the order of 1 kW/sq cm), which in turn causes the photon to photon conversion efficiency to approach the quantum efficiency (76 percent for Nd:YAG at 1.06 microns pumped at 0.810 micron). This is achieved despite the dual-lobed nature of the pump. Through the use of simple beam-combining schemes (e.g., polarization coupling and multireflection point pumping), output powers over 1 W and overall electrical to optical efficiencies as high as 10 percent are expected.

  15. Synchronization of bandwidth-enhanced chaos in semiconductor lasers with optical feedback and injection.

    PubMed

    Someya, Hiroyuki; Oowada, Isao; Okumura, Haruka; Kida, Takahiko; Uchida, Atsushi

    2009-10-26

    We experimentally investigate the generation and synchronization of bandwidth-enhanced chaos in a semiconductor laser (drive laser) that is subject to optical injection from another chaotic semiconductor laser (injection laser) with optical feedback. Effective bandwidth enhancement is achieved over 12 GHz, under the condition in which the optical wavelength of the drive laser is positively detuned with respect to that of the injection laser, outside the injection locking range. The bandwidth-enhanced chaotic signal of the drive laser is injected into a third semiconductor laser (response laser) for synchronization. Synchronization of chaos with a bandwidth greater than 12 GHz is observed between the drive and response lasers, under the condition in which the optical wavelength of the response laser is negatively detuned with respect to that of the drive laser, satisfying the injection locking condition. High-quality chaos synchronization is observed within the injection locking range between the drive and response lasers and under the condition of a low relaxation oscillation frequency of the response laser.

  16. Low spatial coherence electrically pumped semiconductor laser for speckle-free full-field imaging.

    PubMed

    Redding, Brandon; Cerjan, Alexander; Huang, Xue; Lee, Minjoo Larry; Stone, A Douglas; Choma, Michael A; Cao, Hui

    2015-02-03

    The spatial coherence of laser sources has limited their application to parallel imaging and projection due to coherent artifacts, such as speckle. In contrast, traditional incoherent light sources, such as thermal sources or light emitting diodes (LEDs), provide relatively low power per independent spatial mode. Here, we present a chip-scale, electrically pumped semiconductor laser based on a novel design, demonstrating high power per mode with much lower spatial coherence than conventional laser sources. The laser resonator was fabricated with a chaotic, D-shaped cavity optimized to achieve highly multimode lasing. Lasing occurs simultaneously and independently in ∼1,000 modes, and hence the total emission exhibits very low spatial coherence. Speckle-free full-field imaging is demonstrated using the chaotic cavity laser as the illumination source. The power per mode of the sample illumination is several orders of magnitude higher than that of a LED or thermal light source. Such a compact, low-cost source, which combines the low spatial coherence of a LED with the high spectral radiance of a laser, could enable a wide range of high-speed, full-field imaging and projection applications.

  17. Low spatial coherence electrically pumped semiconductor laser for speckle-free full-field imaging

    PubMed Central

    Redding, Brandon; Cerjan, Alexander; Huang, Xue; Lee, Minjoo Larry; Stone, A. Douglas; Choma, Michael A.; Cao, Hui

    2015-01-01

    The spatial coherence of laser sources has limited their application to parallel imaging and projection due to coherent artifacts, such as speckle. In contrast, traditional incoherent light sources, such as thermal sources or light emitting diodes (LEDs), provide relatively low power per independent spatial mode. Here, we present a chip-scale, electrically pumped semiconductor laser based on a novel design, demonstrating high power per mode with much lower spatial coherence than conventional laser sources. The laser resonator was fabricated with a chaotic, D-shaped cavity optimized to achieve highly multimode lasing. Lasing occurs simultaneously and independently in ∼1,000 modes, and hence the total emission exhibits very low spatial coherence. Speckle-free full-field imaging is demonstrated using the chaotic cavity laser as the illumination source. The power per mode of the sample illumination is several orders of magnitude higher than that of a LED or thermal light source. Such a compact, low-cost source, which combines the low spatial coherence of a LED with the high spectral radiance of a laser, could enable a wide range of high-speed, full-field imaging and projection applications. PMID:25605946

  18. Multi-phonon-assisted absorption and emission in semiconductors and its potential for laser refrigeration

    SciTech Connect

    Khurgin, Jacob B.

    2014-06-02

    Laser cooling of semiconductors has been an elusive goal for many years, and while attempts to cool the narrow gap semiconductors such as GaAs are yet to succeed, recently, net cooling has been attained in a wider gap CdS. This raises the question of whether wider gap semiconductors with higher phonon energies and stronger electron-phonon coupling are better suitable for laser cooling. In this work, we develop a straightforward theory of phonon-assisted absorption and photoluminescence of semiconductors that involves more than one phonon and use to examine wide gap materials, such as GaN and CdS and compare them with GaAs. The results indicate that while strong electron-phonon coupling in both GaN and CdS definitely improves the prospects of laser cooling, large phonon energy in GaN may be a limitation, which makes CdS a better prospect for laser cooling.

  19. Semiconductor Laser Theory: The Maxwell--Bloch Equations

    NASA Astrophysics Data System (ADS)

    Gehrig, Edeltraud; Hess, Ortwin

    Because of its central importance for fundamental physics as well as for technological applications, the electronic structure of layered semiconductor structures has attracted much interest over the last two decades. In theoretical studies, methods based on the envelope function approximation are predominant, the reason being that the EFA allows a comprehensive description of electron- and hole-like states. It can cope with periodic or aperiodic geometries of quantum structures, as well as perturbations such as a magnetic field, strain, or a built-in or external potential. Details of the underlying crystal potential are included in terms of bulk band structure parameters.

  20. Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid (Inventor)

    1990-01-01

    An Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 micron radiation with a pump power to output power of efficiency as high as 68 percent. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77 K with an efficiency as high as 68 percent up to ambient room temperature with an efficiency at that temperature as high as 9 percent.

  1. Emergence of resonant mode-locking via delayed feedback in quantum dot semiconductor lasers.

    PubMed

    Tykalewicz, B; Goulding, D; Hegarty, S P; Huyet, G; Erneux, T; Kelleher, B; Viktorov, E A

    2016-02-22

    With conventional semiconductor lasers undergoing external optical feedback, a chaotic output is typically observed even for moderate levels of the feedback strength. In this paper we examine single mode quantum dot lasers under strong optical feedback conditions and show that an entirely new dynamical regime is found consisting of spontaneous mode-locking via a resonance between the relaxation oscillation frequency and the external cavity repetition rate. Experimental observations are supported by detailed numerical simulations of rate equations appropriate for this laser type. The phenomenon constitutes an entirely new mode-locking mechanism in semiconductor lasers.

  2. Irradiation effect of polarization direction and intensity of semiconductor laser on injured peripheral nerve

    NASA Astrophysics Data System (ADS)

    Guo-Xin, Xiong; Lei-lei, Xiong

    2016-08-01

    To investigate the irradiation effect of polarization direction and the intensity of a semiconductor laser on the injured peripheral nerve in rabbits, the model of the injured common peroneal nerve was established, the L5,6 spinal segments of the rabbits were irradiated, a uniform rotating polarizer was placed at the laser output which made the polarization direction and intensity of the output laser change according to the 80 Hz cosine law. The experimental results show that irradiating the spinal segment of injured nerves in rabbits with this changeable semiconductor laser can significantly promote the regeneration of injured peripheral nerves and the function recovery.

  3. Phase noise reduction of a semiconductor laser in a composite optical phase-locked loop

    NASA Astrophysics Data System (ADS)

    Satyan, Naresh; Sendowski, Jacob; Vasilyev, Arseny; Rakuljic, George; Yariv, Amnon

    2010-12-01

    The bandwidth and residual phase noise of optical phase-locked loops (OPLLs) using semiconductor lasers are typically constrained by the nonuniform frequency modulation response of the laser, limiting their usefulness in a number of applications. It is shown in this work that additional feedback control using an optical phase modulator improves the coherence between the master and slave lasers in the OPLL by achieving bandwidths determined only by the propagation delay in the loop. A phase noise reduction by more than a factor of two is demonstrated in a proof-of-concept experiment using a commercial distributed feedback semiconductor laser.

  4. Extracting physical properties of arbitrarily shaped laser-doped micro-scale areas in semiconductors

    SciTech Connect

    Heinrich, Martin; Kluska, Sven; Hameiri, Ziv; Hoex, Bram; Aberle, Armin G.

    2013-12-23

    We present a method that allows the extraction of relevant physical properties such as sheet resistance and dopant profile from arbitrarily shaped laser-doped micro-scale areas formed in semiconductors with a focused pulsed laser beam. The key feature of the method is to use large laser-doped areas with an identical average number of laser pulses per area (laser pulse density) as the arbitrarily shaped areas. The method is verified using sheet resistance measurements on laser-doped silicon samples. Furthermore, the method is extended to doping with continuous-wave lasers by using the average number of passes per area or density of passes.

  5. Ultrafast supercontinuum fiber-laser based pump-probe scanning magneto-optical Kerr effect microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution

    SciTech Connect

    Henn, T.; Kiessling, T. Ossau, W.; Molenkamp, L. W.; Biermann, K.; Santos, P. V.

    2013-12-15

    We describe a two-color pump-probe scanning magneto-optical Kerr effect microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast “white light” supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables the investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of the instrument.

  6. Lifetime of high-power GaAs photoconductive semiconductor switch triggered by laser of different power density

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Wang, Wei; Shen, Yi; Shi, Jinshui; Zhang, Linwen; Xia, Liansheng

    2015-02-01

    Conduction modes of GaAs photoconductive semiconductor switch (PCSS) and their conditions are expounded. Laser diode and high-power picosecond Nd:YAG lasers are used as triggers for nonlinear mode and quasi-linear mode respectively in high-power conduction experiment. GaAs PCSS`s failure mechanisms and factors influencing lifetime in both modes are analyzed. It is found that the power density of laser at trigger time determines in which mode GaAs PCSS operates. Low-power laser triggers a nonlinear mode conduction in which GaAs PCSS`s lifetime is only 103, while high-power laser triggers a quasi-linear mode conduction in which GaAs PCSS`s lifetime is up to 105. According to the findings, the compact high-power pulsed power system based on mass of GaAs PCSSs demands for miniature high-power laser generators.

  7. Non-Shilnikov cascades of spikes and hubs in a semiconductor laser with optoelectronic feedback.

    PubMed

    Freire, Joana G; Gallas, Jason A C

    2010-09-01

    Incomplete homoclinic scenarios were recently measured in a semiconductor laser with optoelectronic feedback. We show here that such a laser contains cascades of spirals of periodic oscillations and hubs which look identical to the familiar ones observed in complete homoclinic scenarios. This means that hubs are far more general than presumed so far, being not limited by Shilnikov's theorem. Laser hubs open the possibility of measuring complex distributions of non-Shilnikov laser oscillations, and we briefly discuss how to do it.

  8. Incorporating many-body effects into modeling of semiconductor lasers and amplifiers

    SciTech Connect

    Ning, C.Z.; Moloney, J.V.; Indik, R.A.

    1997-06-01

    Major many-body effects that are important for semiconductor laser modeling are summarized. The authors adopt a bottom-up approach to incorporate these many-body effects into a model for semiconductor lasers and amplifiers. The optical susceptibility function ({Chi}) computed from the semiconductor Bloch equations (SBEs) is approximated by a single Lorentzian, or a superposition of a few Lorentzians in the frequency domain. Their approach leads to a set of effective Bloch equations (EBEs). The authors compare this approach with the full microscopic SBEs for the case of pulse propagation. Good agreement between the two is obtained for pulse widths longer than tens of picoseconds.

  9. Techniques for increasing output power from mode-locked semiconductor lasers

    SciTech Connect

    Mar, A.; Vawter, G.A.

    1996-02-01

    Mode-locked semiconductor lasers have drawn considerable attention as compact, reliable, and relatively inexpensive sources of short optical pulses. Advances in the design of such lasers have resulted in vast improvements in pulsewidth and noise performance, at a very wide range of repetition rates. An attractive application for these lasers would be to serve as alternatives for large benchtop laser systems such as dye lasers and solid-state lasers. However, mode-locked semiconductor lasers have not yet approached the performance of such systems in terms of output power. Different techniques for overcoming the problem of low output power from mode-locked semiconductor lasers will be discussed. Flared and arrayed lasers have been used successfully to increase the pulse saturation energy limit by increasing the gain cross section. Further improvements have been achieved by use of the MOPA configuration, which utilizes a flared semiconductor amplifier s amplify pulses to energies of 120 pJ and peak powers of nearly 30W.

  10. Numerical analysis of thermal effects in semiconductor disk laser with TEC cooler

    NASA Astrophysics Data System (ADS)

    Zhu, Renjiang; Zhang, Peng; Jiang, Maohua

    2016-11-01

    Based on generalized heat transfer model of thermoelectric cooler(TEC), the heat management model of semiconductor disk laser with TEC cooler has been built. With finite element method, this article has calculated the temperature distribution characteristics, and studied the effects of TEC current, heat exchange coefficient, the heatsink and the pump laser for the maximum temperature of quantum wells. Calculations show that the heat transfer coefficient significantly affects the ability of the TEC temperature shift, cooling system performance which is nearly inversely proportional to the heatsink thermal conductivity is not sensitive to its the thickness variation, and the performance of oxygen-free copper with optimization of the area is close to diamond. Meanwhile the maximum temperature of the quantum well has a linear relationship with the pump power, and increasing the pump spot size is an effective way to increase the optical power output

  11. Self-injected semiconductor distributed feedback lasers for frequency chirp stabilization.

    PubMed

    Kechaou, Khalil; Grillot, Frédéric; Provost, Jean-Guy; Thedrez, Bruno; Erasme, Didier

    2012-11-05

    It is well known that semiconductor distributed feedback lasers (DFB) are key devices for optical communications. However direct modulation applications are limited by the frequency chirp induced by current modulation. We demonstrate that a proper external control laser operation leads to chirp-to-power ratio (CPR) stabilization over a wide range of modulation frequencies as compared to the free-running case. Under experimentally selected optical feedback conditions, the CPR decreases significantly in the adiabatic regime from about 650 MHz/mW in the solitary case down to 65 MHz/mW. Experimental results are also confirmed by numerical investigations based on the transfer matrix method. Simulations point out the possible optimization of the CPR in the adiabatic regime by considering a judicious cavity design in conjunction with a proper external control. These results demonstrate important routes for improving the transmission performance in optical telecommunication systems.

  12. Ultrashort pulse generation by semiconductor mode-locked lasers at 760 nm.

    PubMed

    Wang, Huolei; Kong, Liang; Forrest, Adam; Bajek, David; Haggett, Stephanie E; Wang, Xiaoling; Cui, Bifeng; Pan, Jiaoqing; Ding, Ying; Cataluna, Maria Ana

    2014-10-20

    We demonstrate the first semiconductor mode-locked lasers for ultrashort pulse generation at the 760 nm waveband. Multi-section laser diodes based on an AlGaAs multi-quantum-well structure were passively mode-locked, resulting in the generation of pulses at around 766 nm, with pulse durations down to ~4 ps, at pulse repetition rates of 19.4 GHz or 23.2 GHz (with different laser cavity lengths of 1.8 mm and 1.5 mm, respectively). The influence of the bias conditions on the mode-locking characteristics was investigated for these new lasers, revealing trends which can be ascribed to the interplay of dynamical processes in the saturable absorber and gain sections. It was also found that the front facet reflectivity played a key role in the stability of mode-locking and the occurrence of self-pulsations. These lasers hold significant promise as light sources for multi-photon biomedical imaging, as well as in other applications such as frequency conversion into the ultraviolet and radio-over-fibre communications.

  13. Semiconductor nanocrystal-based phagokinetic tracking

    SciTech Connect

    Alivisatos, A Paul; Larabell, Carolyn A; Parak, Wolfgang J; Le Gros, Mark; Boudreau, Rosanne

    2014-11-18

    Methods for determining metabolic properties of living cells through the uptake of semiconductor nanocrystals by cells. Generally the methods require a layer of neutral or hydrophilic semiconductor nanocrystals and a layer of cells seeded onto a culture surface and changes in the layer of semiconductor nanocrystals are detected. The observed changes made to the layer of semiconductor nanocrystals can be correlated to such metabolic properties as metastatic potential, cell motility or migration.

  14. Tunable Yb:CaF2-SrF2 laser and femtosecond mode-locked performance based on semiconductor saturable absorber mirrors.

    PubMed

    Zhang, Feng; Zhu, Hongtong; Liu, Jie; He, Yifeng; Jiang, Dapeng; Tang, Fei; Su, Liangbi

    2016-10-10

    We experimentally demonstrate an effective continuous-wave tunable operation and femtosecond passively mode-locked pulse from a Yb:CaF2-SrF2 mixed crystal laser for the first time. Pumped by a 977 nm fiber-coupled laser diode, a continuous-wave mode-locked pulse as short as 634 fs was generated. The shortest pulse operated under a repetition rate of 87 MHz at the central wavelength of 1047 nm. The calculated time-bandwidth product was 0.503, which was 1.6 times the Fourier transform-limited sech2-shaped pulses.

  15. CONTROL OF LASER RADIATION PARAMETERS: Harmonic modulation of radiation of an external-feedback semiconductor laser

    NASA Astrophysics Data System (ADS)

    Sukharev, Aleksandr G.; Napartovich, A. P.

    2007-02-01

    The appearance of the harmonic modulation regime at the Hopf bifurcation point is described analytically for a delayed-feedback semiconductor laser. The second-order delay differential equation with complex coefficients is derived. The frequency of oscillations appearing at the Hopf bifurcation point is determined by the solution of two relatively simple transcendental equations, from which the bifurcation point itself is found. These equations contain dependences on all the control parameters of the problem. The exact upper and lower limits of the oscillation frequency are found. A comparison with numerical results shows that the modulation frequency is preserved almost constant in a broad range of feedback phases. A procedure is proposed for determining the parameters of the laser providing the presence of bifurcations with a passage to oscillations with the specified frequency. The results obtained in the paper are of interest for WDM communication systems.

  16. Intensity noise reduction in semiconductor lasers by amplitude-phase decorrelation

    NASA Technical Reports Server (NTRS)

    Vahala, Kerry J.; Newkirk, Michael A.

    1990-01-01

    Detuned operation of a laser results in coupling of field amplitude and phase fluctuations. In a semiconductor laser, this coupling is known to be very large. Here it is demonstrated that it can be used to significantly reduce intensity noise below its intrinsic limit.

  17. Study of the emission spectra of a 1320-nm semiconductor disk laser and its second harmonic

    SciTech Connect

    Gochelashvili, K S; Derzhavin, S I; Evdokimova, O N; Zolotovskii, I O; Podmazov, S V

    2016-03-31

    The spectral characteristics of an optically pumped external-cavity semiconductor disk laser near λ = 1320 nm are studied experimentally. Intracavity second harmonic generation is obtained using an LBO nonlinear crystal. The output power at a wavelength of 660 nm in the cw regime was 620 mW, and the peak power in the pulsed regime was 795 mW. (lasers)

  18. Parametric distortion of the optical absorption edge of a magnetic semiconductor by a strong laser field

    SciTech Connect

    Nunes, O.A.C.

    1985-09-15

    The influence of a strong laser field on the optical absorption edge of a direct-gap magnetic semiconductor is considered. It is shown that as the strong laser intensity increases the absorption coefficient is modified so as to give rise to an absorption tail below the free-field forbidden gap. An application is made for the case of the EuO.

  19. Cubic zirconia as a high-quality facet coating for semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Chin, A. K.; Satyanarayan, A.; Zarrabi, J. H.; Vetterling, W.

    1988-08-01

    In this paper we describe the properties of high-quality, semiconductor laser facet coatings based on yttria-stabilizied cubic zirconia (90-m% ZrO2/10-m% Y2O3). We have found that cubic zirconia films can be reproducibly deposited by electron-beam evaporation with an index of refraction of 1.98 at 6328 Å, almost ideal for use as a single-layer antireflection coating for GaAs/GaAlAs-based lasers. ZrO2 has a monoclinic crystal structure at room temperature, but changes to tetragonal, hexagonal, and cubic phases upon heating to higher temperatures. However, the addition of the Y2O3 stabilizes ZrO2 in the cubic form, thus allowing electron-beam deposition of thin films of this material to be more controllable and reproducible without the usual addition of oxygen into the vacuum chamber during deposition. Preliminary aging tests of high-power GaAs/GaAlAs lasers show that cubic zirconia films suppress the photo-enhanced oxidation of laser facets that degrades device performance.

  20. Narrow linewidth single-mode semiconductor laser development for coherent detection lidar

    NASA Technical Reports Server (NTRS)

    Mansour, Kamjou; Ksendzov, Alexander; Menzies, Robert T.; Maker, Paul D.; Muller, Richard E.; Manfra, M. J.; Turner, George W.

    2003-01-01

    High power, tunable, single mode, narrow linewidth semiconductor lasers in the 2.05-(micro)m wavelength region are needed to develop semiconductor laser reference oscillators for optical remote sensing from Earth orbit. 2.05-I1/4m narrow linewidth monolithic distributed feedback (DFB) and distributed Bragg reflector (DBR) with the external grating ridge waveguide lasers fabricated from epitaxially grown InGaAs/InGaAsP/InP and in InGaAsSb/AlGaAsSb/GaSb heterostructures are reported.

  1. Rate-equation model for multi-mode semiconductor lasers with spatial hole burning.

    PubMed

    Lenstra, Daan; Yousefi, Mirvais

    2014-04-07

    We present a set of rate equations for the modal amplitudes and carrier-inversion moments that describe the deterministic multi-mode dynamics of a semiconductor laser due to spatial hole burning. Mutual interactions among the lasing modes, induced by high- frequency modulations of the carrier distribution, are included by carrier-inversion moments for which rate equations are given as well. We derive the Bogatov effect of asymmetric gain suppression in semiconductor lasers and illustrate the potential of the model for a two and three-mode laser by numerical and analytical methods.

  2. Room-temperature-operation visible-emission semiconductor diode lasers

    NASA Technical Reports Server (NTRS)

    Ladany, I.; Kressel, H.; Nuese, C. J.

    1977-01-01

    There were two main approaches taken to develop shorter wavelength lasers. (1) Based on (AlGa)As and liquid-phase epitaxy, significant new results were obtained: Properties of these laser diodes (power output, spectra, and beam patterns), materials considerations, laser theory, and growth problems are discussed. The design of (AlGa)As layers is discussed from the vertical point of view, and various design curves are given. Horizontal structural requirements are also discussed. Experimental results from measurements done as a function of hydrostatic pressure are correlated with other results. (2) The first heterojunction laser structures using GaAs sub l-x P sub x and In sub y Ga sub l-y P at compositions, where the lattice constants are matched, were grown using vapor-phase growth technology and are described in detail, including experimental device results. Threshold current densities from 3,000 to 5,000 A per sq cm. and emission wavelengths from 6,520 A to 6,640 A were obtained at 77 K. The limiting factor in these devices is nonradiative recombination at the heterojunctions. Life tests on facet-coated (AlGa)As CW diodes are reported.

  3. A study on the optical parts for a semiconductor laser module

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Girl; Lee, Dong-Kil; Kim, Yang-Gyu; Lee, Kwang-Hoon; Park, Young-Sik; Jang, Kwang-Ho; Kang, Seung-Goo

    2014-11-01

    A semiconductor laser module consists of a LD (laser diode) chip that generates a laser beam, two cylindrical lenses to collimate the laser beam, a high-reflection mirror to produce a large output by collecting the laser beam, a collimator lens to guide the laser beam to an optical fiber and a protection filter to block reflected laser light that might damage the LD chip. The cylindrical lenses used in a semiconductor laser module are defined as FACs (fast axis collimators) and SACs (slow axis collimators) and are attached to the system module to control the shape of the laser beam. The FAC lens and the SAC lens are made of a glass material to protect the lenses from thermal deformation. In addition, they have aspheric shapes to improve optical performances. This paper presents a mold core grinding process for an asymmetrical aspheric lens and a GMP (glass molding press), what can be used to make aspheric cylindrical lenses for use as FACs or SACs, and a protection filter made by using IAD (ion-beam-assisted deposition). Finally, we developed the aspheric cylindrical lenses and the protection filter for a 10-W semiconductor laser module.

  4. Ionization balance in semiconductor quantum-dot lasers

    NASA Astrophysics Data System (ADS)

    Pan, Janet L.

    1994-01-01

    The commonly assumed quasiequilibrium particle distribution with the same quasi-Fermi-level for all quantum-dot carriers in the same energy (conduction or valence) band is found not to be valid for a wide range of temperatures at the inversion populations and bound energy separations (greater than a LO phonon energy) used in the literature. Bound state occupation factors obtained from the steady state solution of rate equations describing the ionization balance in room-temperature 100-Å-radius GaAs quantum dots whose centers are separated by 400 Å are found to be very different from the quasiequilibrium distribution used in an example from the literature. In such quantum dots, bound state transitions result from collisions between charged particles via the Coulomb interaction, and from interband and intraband radiative processes. The critical free electron concentration above which collisional processes can establish a quasiequilibrium in the conduction band is found to exceed 1019 cm-3. Our numerical solution is in good agreement with Pitaevskii's model from atomic physics of an electron random walk in energy as modeled by a Fokker-Planck equation. In our simple model, electrons are captured into a bound conduction band state via three-body recombination and phonon emission, and drop into lower energy bound states via a series of collisional deexcitations before combining with a valence band hole. Solution of the rate equations is standard in numerical studies of stimulated emission in atomic plasmas, but our present discussion is, to our knowledge, the first in the literature on semiconductor quantum-dot lasers.

  5. A Hydrodynamic Theory for Spatially Inhomogeneous Semiconductor Lasers: Microscopic Approach

    NASA Technical Reports Server (NTRS)

    Li, Jianzhong; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)

    2001-01-01

    Starting from the microscopic semiconductor Bloch equations (SBEs) including the Boltzmann transport terms in the distribution function equations for electrons and holes, we derived a closed set of diffusion equations for carrier densities and temperatures with self-consistent coupling to Maxwell's equation and to an effective optical polarization equation. The coherent many-body effects are included within the screened Hartree-Fock approximation, while scatterings are treated within the second Born approximation including both the in- and out-scatterings. Microscopic expressions for electron-hole (e-h) and carrier-LO (c-LO) phonon scatterings are directly used to derive the momentum and energy relaxation rates. These rates expressed as functions of temperatures and densities lead to microscopic expressions for self- and mutual-diffusion coefficients in the coupled density-temperature diffusion equations. Approximations for reducing the general two-component description of the electron-hole plasma (EHP) to a single-component one are discussed. In particular, we show that a special single-component reduction is possible when e-h scattering dominates over c-LO phonon scattering. The ambipolar diffusion approximation is also discussed and we show that the ambipolar diffusion coefficients are independent of e-h scattering, even though the diffusion coefficients of individual components depend sensitively on the e-h scattering rates. Our discussions lead to new perspectives into the roles played in the single-component reduction by the electron-hole correlation in momentum space induced by scatterings and the electron-hole correlation in real space via internal static electrical field. Finally, the theory is completed by coupling the diffusion equations to the lattice temperature equation and to the effective optical polarization which in turn couples to the laser field.

  6. IV-VI semiconductor growth on silicon substrates and new mid-infrared laser fabrication methods

    PubMed

    McCann; Chao; Sachar; McAlister; Li; Fang; Wu; Namjou

    1999-09-01

    This paper reviews results from research conducted at the University of Oklahoma on the development of new IV-VI semiconductor (lead salt) epitaxial growth and laser fabrication procedures that can ultimately lead to dramatic increases in mid-IR laser operating temperatures. Work has focused on growth of IV-VI semiconductor laser structures on silicon substrates using buffer layers that contain BaF2. Recent experiments show that it is possible to obtain high crystalline quality IV-VI semiconductor layer structures on (111)-oriented silicon substrates using molecular beam epitaxy (MBE) or on (100)-oriented silicon using a combination of MBE and liquid phase epitaxy (LPE). Experimental data for IV-VI semiconductor layer structures grown on silicon substrates including crystalline quality information as determined by high resolution X-ray diffraction (HRXRD) measurements and absorption edge information as determined by Fourier transform infrared (FTIR) transmission measurements are presented. Results show that these materials can be used to fabricate lasers that cover the 3 microns (3333 cm-1) to 16 microns (625 cm-1) spectral range. Removal of IV-VI semiconductor laser structures from the silicon growth substrate by dissolving BaF2 buffer layers with water is also demonstrated. This allows epitaxially-grown laser structures to be sandwiched between two heat sinks with a minimum of thermally resistive IV-VI semiconductor material. Theoretical modeling predicts that IV-VI lasers fabricated this way will have maximum continuous wave (cw) operating temperatures at least 60 degrees higher than those of IV-VI lasers fabricated on PbSe or PbTe substrates.

  7. High power single-frequency continuously-tunable compact extended-cavity semiconductor laser.

    PubMed

    Laurain, A; Myara, M; Beaudoin, G; Sagnes, I; Garnache, A

    2009-06-08

    We demonstrate high power high efficiency (0:3 W) low noise single frequency operation of a compact extended-cavity surface-emitting-semiconductor-laser exhibiting a continuous tunability over 0:84 THz with high beam quality. We took advantage of thermal lens-based stability to develop a short (< 3 mm) plano-plano external cavity without any intracavity filter. The structure is optically pumped by a 1 W commercial 830 nm multimode diode laser. No heat management was required. We measured a low divergence circular TEM(00) beam at the diffraction limit (M(2) < 1:05) with a linear light polarization (> 37 dB). The side mode suppression ratio is 60 dB. The free running laser linewidth is 850 kHz limited by pump induced thermal fluctuations. Thanks to this high-Q external cavity approach, the frequency noise is low and the dynamics is in the relaxation-oscillation-free regime, exhibiting a low intensity noise, with a cutoff frequency approximately 250 MHz above which the shot noise level is reached. We show that pump properties define the cavity design and laser coherence.

  8. New semiconductor diode laser emitting at 2 um for microsurgery applications

    NASA Astrophysics Data System (ADS)

    Gobbi, Pier Giorgio; Ragazzi, D.; Azzolini, Claudio; Trabucchi, Giuseppe; Brancato, Rosario

    1996-01-01

    A surgical laser instrument is presented, based on a semiconductor diode emitting in the spectral region around 2 micrometer, in continuous mode. At this wavelength tissue absorption is via histological water, and the interaction is purely thermal. A portable laser station was built, emitting up to 250 mW of optical power at 1.94 micrometers, out of the tip of a low- hydroxil fused-silica optical fiber of 200 micrometer diameter. Experiments have been performed both in vitro with enucleated porcine eyes and in vivo, on rabbits and rats. In vitreo-retinal surgery, retinectomies and incisions of epiretinal fibrotic membranes have been achieved. At reduced output power the laser radiation has been applied to the welding of tissues, in particular cornea, sclera and skin, with interesting results. This new laser source, characterized by ergonomic advantages like compactness, portability, long lifetime, reduced maintenance, is potentially attractive for a number of microsurgical procedures like micro- incisions, shallow coagulations, and welding of hydrated biological membranes.

  9. Nanoimprinted organic semiconductor laser pumped by a light-emitting diode.

    PubMed

    Tsiminis, Georgios; Wang, Yue; Kanibolotsky, Alexander L; Inigo, Anto R; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A

    2013-05-28

    An organic semiconductor laser, simply fabricated by UV-nanoimprint lithography (UV-NIL), that is pumped with a pulsed InGaN LED is demonstrated. Molecular weight optimization of the polymer gain medium on a nanoimprinted polymer distributed feedback resonator enables the lowest reported UV-NIL laser threshold density of 770 W cm(-2) , establishing the potential for scalable organic laser fabrication compatible with mass-produced LEDs.

  10. Generation of high-power ultrashort optical pulses by semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Dudelev, V. V.; Zazulin, S. V.; Kolykhalova, E. D.; Losev, S. N.; Deryagin, A. G.; Kuchinskii, V. I.; Efanov, M. V.; Sokolovskii, G. S.

    2016-12-01

    Fiber-coupled semiconductor lasers have been studied when pumped by high-power short electrical pulses of 5 ns width and leading front duration below 1 ns. In this pumping regime, it is possible to ensure significant sharpening of output pulses, the duration of which decreases below 80 ps for a single-mode laser and below 120 ps for a broad aperture multimode laser at an output peak optical power as high as 1.5 and 27 W, respectively.

  11. Semiconductor laser with a birefringent external cavity for information systems with wavelength division multiplexing

    SciTech Connect

    Paranin, V D; Matyunin, S A; Tukmakov, K N

    2013-10-31

    The spectrum of a semiconductor laser with a birefringent external Gires – Tournois cavity is studied. The generation of two main laser modes corresponding to the ordinary and extraordinary wave resonances is found. It is shown that the radiation spectrum is controlled with a high energy efficiency without losses for spectral filtration. The possibility of using two-mode lasing in optical communication systems with wavelength division multiplexing is shown. (control of laser radiation parameters)

  12. Two-photon fluorescence bioimaging with an all-semiconductor laser picosecond pulse source.

    PubMed

    Kuramoto, Masaru; Kitajima, Nobuyoshi; Guo, Hengchang; Furushima, Yuji; Ikeda, Masao; Yokoyama, Hiroyuki

    2007-09-15

    We have demonstrated successful two-photon excitation fluorescence bioimaging using a high-power pulsed all-semiconductor laser. Toward this purpose, we developed a pulsed light source consisting of a mode-locked laser diode and a two-stage diode laser amplifier. This pulsed light source provided optical pulses of 5 ps duration and having a maximum peak power of over 100 W at a wavelength of 800 nm and a repetition frequency of 500 MHz.

  13. Relative refractory period in an excitable semiconductor laser.

    PubMed

    Selmi, F; Braive, R; Beaudoin, G; Sagnes, I; Kuszelewicz, R; Barbay, S

    2014-05-09

    We report on experimental evidence of neuronlike excitable behavior in a micropillar laser with saturable absorber. We show that under a single pulsed perturbation the system exhibits subnanosecond response pulses and analyze the role of the laser bias pumping. Under a double pulsed excitation we study the absolute and relative refractory periods, similarly to what can be found in neural excitability, and interpret the results in terms of a dynamical inhibition mediated by the carrier dynamics. These measurements shed light on the analogy between optical and biological neurons and pave the way to fast spike-time coding based optical systems with a speed several orders of magnitude faster than their biological or electronic counterparts.

  14. Reaction-diffusion optoelectronics based on dispersed semiconductors

    NASA Astrophysics Data System (ADS)

    Gradov, O. V.; Gradova, M. A.

    2015-11-01

    Since many dispersed semiconductors are capable of light energy conversion and possess photocatalytic and luminescent properties, and any discreet light-sensitive medium can be applied for the positional-sensitive light flux registration (similar to pixels and voxels in semiconductor-based image recording), the use of chemically active dispersed semiconductors allows to perform a direct signal / image registration based on light-sensitive reaction-diffusion redox systems without conventional CCD / CMOS devices. The image capturing in this case will correspond to the formation of the metastable dissipative structures in the active medium, with their morphological properties determined by the flux gradient and provided by the corresponding dispersed semiconductor medium sensitivity.

  15. Above 2-μm emitting GaSb-based semiconductor disk laser with <100-kHz linewidth at 1000-mW output power

    NASA Astrophysics Data System (ADS)

    Kaspar, Sebastian; Rattunde, Marcel; Töpper, Tino; Rösener, Benno; Manz, Christian; Köhler, Klaus; Wagner, Joachim

    2012-03-01

    In this paper we report on the development of narrow-linewidth vertical-external-cavity surface-emitting laser (VECSEL) at a wavelength of >2 μm. Starting from a laboratory setup, we designed a highly stable VECSEL module machined from a solid block of aluminum. For linewidth precise measurements, heterodyne beatnote measurements were employed. For this firstgeneration module a linewidth of 9 kHz was achieved when actively stabilizing the laser wavelength, whereas without stabilization the linewidth amounted to 45 kHz at an output power of 100 mW, both data referring to a 100-μs sampling time. To further increase the output power, a second-generation module was fabricated, for which the on-chip mode diameter was increased. This allowed operation at a larger pump-spot diameter and still maintaining TEM00 operation, while increasing the maximum pump power and hence the output power. This module yielded an output power above 1 W in single-mode operation at a linewidth of 60 kHz (100 μs sampling time) without active wavelength stabilization. Modehop-free single-mode operation could be maintained for more than 18 hours. This new multiple-Watt, narrow-linewidth VECSEL module is apt for plane-to-ground communications without the necessity of amplifiers.

  16. Plasma Heating and Ultrafast Semiconductor Laser Modulation Through a Terahertz Heating Field

    NASA Technical Reports Server (NTRS)

    Li, Jian-Zhong; Ning, C. Z.

    2000-01-01

    Electron-hole plasma heating and ultrafast modulation in a semiconductor laser under a terahertz electrical field are investigated using a set of hydrodynamic equations derived from the semiconductor Bloch equations. The self-consistent treatment of lasing and heating processes leads to the prediction of a strong saturation and degradation of modulation depth even at moderate terahertz field intensity. This saturation places a severe limit to bandwidth achievable with such scheme in ultrafast modulation. Strategies for increasing modulation depth are discussed.

  17. Generation of terahertz radiation by a surface ballistic photocurrent in semiconductors under subpicosecond laser excitation

    SciTech Connect

    Ziaziulia, P. A.; Malevich, V. L.; Manak, I. S.; Krotkus, A.

    2012-02-15

    An analytical model describing the onset of a surface ballistic photocurrent in cubic semiconductors under femtosecond laser excitation is proposed. It is shown that the contribution of the photocurrent component parallel to the surface to the generation of terahertz pulses may be comparable to the contribution of the perpendicular component. Consideration of the cubic symmetry of a semiconductor leads to the azimuthal anisotropy of terahertz generation.

  18. Demonstration of arbitrary channel selection utilizing a pulse-injected semiconductor laser with a phase-locked loop.

    PubMed

    Juan, Yu-Shan; Lin, Fan-Yi

    2011-01-17

    An arbitrary channel selection system based on a pulse-injected semiconductor laser with a phase-locked loop (PLL) is experimentally demonstrated and characterized. Through optical injection from a tunable laser, channels formed by the frequency components of a microwave frequency comb generated in the pulse-injected semiconductor laser are individually selected and enhanced. Selections of a primary channel at the fundamental frequency of 1.2 GHz and a secondary channel in a range from 10.8 to 18 GHz are shown, where the selection is done by adjusting the injection strength from the tunable laser. Suppression ratios of 44.5 and 25.9 dB between the selected primary and secondary channels to the averaged magnitude of the unwanted channels are obtained, respectively. To show the spectral quality of the pulse-injected laser, a single sideband (SSB) phase noise of -60 dBc/kHz at an offset frequency of 25 kHz is measured. Moreover, the conversion gain between the primary and secondary channels and the crosstalk between the selected channels to the adjacent unwanted channels are also investigated. Without the need of expensive external modulators, arbitrary channel selection is realized in the proposed system where the channel spacing and selection can be continuously adjusted through tuning the controllable laser parameters.

  19. High-power optically pumped semiconductor laser apllications

    NASA Astrophysics Data System (ADS)

    Morioka, S. Brandon

    2011-03-01

    OPS lasers have found applications in various industrial and scientific laser applications due to their power scaling capability, their wide range of emission wavelengths, physical size and their superior reliability. This paper provides an overview of commercially available OPS lasers and the applications in which they are used including biotechnology, medical, holography, Titanium-Sapphire laser pumping, non-lethal defense, forensics, and entertainment.

  20. Thermally robust semiconductor optical amplifiers and laser diodes

    DOEpatents

    Dijaili, Sol P.; Patterson, Frank G.; Walker, Jeffrey D.; Deri, Robert J.; Petersen, Holly; Goward, William

    2002-01-01

    A highly heat conductive layer is combined with or placed in the vicinity of the optical waveguide region of active semiconductor components. The thermally conductive layer enhances the conduction of heat away from the active region, which is where the heat is generated in active semiconductor components. This layer is placed so close to the optical region that it must also function as a waveguide and causes the active region to be nearly the same temperature as the ambient or heat sink. However, the semiconductor material itself should be as temperature insensitive as possible and therefore the invention combines a highly thermally conductive dielectric layer with improved semiconductor materials to achieve an overall package that offers improved thermal performance. The highly thermally conductive layer serves two basic functions. First, it provides a lower index material than the semiconductor device so that certain kinds of optical waveguides may be formed, e.g., a ridge waveguide. The second and most important function, as it relates to this invention, is that it provides a significantly higher thermal conductivity than the semiconductor material, which is the principal material in the fabrication of various optoelectronic devices.

  1. Microscopic Foundation and Simulation of Coupled Carrier-Temperature Diffusions in Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Li, J.; Ning, Cun-Zheng; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    A typical semiconductor-based optoelectronic device, such as a diode laser, consists of three subsystems: an optical field, an electron-hole plasma (EHP), and a host crystal lattice. The physics of such a device involves the interplay of optical, electrical and thermal processes. A proper description of such a device requires that all three processes are treated on equal footing and in a self-consistent fashion. Furthermore, since a semiconductor laser has intrinsic spatial inhomogeneity, such a self-consistency naturally leads to a set of partial differential equations in space and time. There is a significant lacking of research interest and results on the transport aspects of optical devices in the literature with only a few exceptions. Even the most important carrier diffusion coefficient has not been properly derived and studied so far for optically excited plasma, while most of the work adopted results from electronics community where heavily doped semiconductors with mainly one type of carriers are dealt with. The corresponding transport equation for plasma energy or temperature has received even less attention. In this talk we describe our recent results on such a self-consistent derivation of temperature and carrier-density diffusion equations coupled with the lasing process. Starting from the microscopic semiconductor Bloch equations (SBEs) including the Boltzmann transport terms in the distribution function equations for electrons and holes, we derived a closed set of diffusion equations for carrier densities and temperatures with self-consistent coupling to Maxwell's equation and to an effective optical polarization equation. The coherent many-body effects are included within the screened Hartree-Fock approximation, while scatterings are treated within the second Born approximation including both the in- and out-scatterings. Microscopic expressions for electron-hole (e-h) and carrier-LO (c-LO) phonon scatterings are directly used to derive the momentum

  2. Final report on LDRD project: Semiconductor surface-emitting microcavity laser spectroscopy for analysis of biological cells and microstructures

    SciTech Connect

    Gourley, P.L.; McDonald, A.E.; Gourley, M.F.; Bellum, J.

    1997-08-01

    This article discusses a new intracavity laser technique that uses living or fixed cells as an integral part of the laser. The cells are placed on a GaAs based semiconductor wafer comprising one half of a vertical cavity surface-emitting laser. After placement, the cells are covered with a dielectric mirror to close the laser cavity. When photo-pumped with an external laser, this hybrid laser emits coherent light images and spectra that depend sensitively on the cell size, shape, and dielectric properties. The light spectra can be used to identify different cell types and distinguish normal and abnormal cells. The laser can be used to study single cells in real time as a cell-biology lab-on-a-chip, or to study large populations of cells by scanning the pump laser at high speed. The laser is well-suited to be integrated with other micro-optical or micro-fluidic components to lead to micro-optical-mechanical systems for analysis of fluids, particulates, and biological cells.

  3. Time delay signature concealment of optical feedback induced chaos in an external cavity semiconductor laser.

    PubMed

    Wu, Jia-Gui; Xia, Guang-Qiong; Tang, Xi; Lin, Xiao-Dong; Deng, Tao; Fan, Li; Wu, Zheng-Mao

    2010-03-29

    The time delay (TD) signature concealment of optical feedback induced chaos in an external cavity semiconductor laser is experimentally demonstrated. Both the evolution curve and the distribution map of TD signature are obtained in the parameter space of external feedback strength and injection current. The optimum parameter scope of the TD signature concealment is also specified. Furthermore, the approximately periodic evolution relation between TD signature and external cavity length is observed and indicates that the intrinsic relaxation oscillation of semiconductor laser may play an important role during the process of TD signature suppression.

  4. Noise spectra of a semiconductor ring laser in the bidirectional regime

    SciTech Connect

    Perez-Serrano, Antonio; Zambrini, Roberta; Scire, Alessandro; Colet, Pere

    2009-10-15

    We analytically investigate the influence of complex backscattering coefficients and pump current on the noise spectra of a two-mode model for semiconductor ring laser in the Langevin formulation. The system features in the bidirectional regime are naturally described in terms of the two mode-intensity sum (I spectrum) and difference (D spectrum). The I spectrum reflects the energy exchange between the total field and the medium and behaves similarly to the relative intensity noise for single-mode semiconductor lasers. The D spectrum represents the energy exchange between the two counterpropagating modes and is shaped by the noisy precursor of a Hopf bifurcation induced by the complex backscattering.

  5. Semiconductor-based, large-area, flexible, electronic devices on {110}<100> oriented substrates

    SciTech Connect

    Goyal, Amit

    2014-08-05

    Novel articles and methods to fabricate the same resulting in flexible, oriented, semiconductor-based, electronic devices on {110}<100> textured substrates are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  6. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  7. Dynamic behaviors of semiconductor lasers under strong sinusoidal current modulation; Modeling and experiments at 1. 3. mu. m

    SciTech Connect

    Hemery, E. ); Chusseau, L.; Lourtioz, J.M. )

    1990-04-01

    A theoretical and experimental study of the dynamic behaviors of semiconductor lasers under strong sinusoidal modulation is presented. The theoretical analysis is based on rate-equations including gain-compression effects. General criteria are established to predict the existence of irregular behaviors. Experiments are performed on a single-mode buried-heterostructure InGaAsP laser at 1.3 {mu}m. An original method is proposed to evaluate the parameters entering the rate equations. Fully optical measurements are used. The nonlinear gain coefficient and the electrical response of the packaged laser are simultaneously determined from small-signal characteristics. Time-domain measurements show the three behaviors achieved with the studied laser, i.e., simple periodic, periodic with multiple spikes, and period doubling.

  8. Curved grating fabrication techniques for concentric-circle grating, surface-emitting semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Jordan, Rebecca H.; King, Oliver; Wicks, Gary W.; Hall, Dennis G.; Anderson, Erik H.; Rooks, Michael J.

    1993-01-01

    We describe the fabrication and operational characteristics of a novel, surface-emitting semiconductor laser that makes use of a concentric-circle grating to both define its resonant cavity and to provide surface emission. A properly fabricated circular grating causes the laser to operate in radially inward- and outward-going circular waves in the waveguide, thus, introducing the circular symmetry needed for the laser to emit a beam with a circular cross-section. The basic circular-grating-resonator concept can be implemented in any materials system; an AlGaAs/GaAs graded-index, separate confinement heterostructure (GRINSCH), single-quantum-well (SQW) semiconductor laser, grown by molecular beam epitaxy (MBE), was used for the experiments discussed here. Each concentric-circle grating was fabricated on the surface of the AlGaAs/GaAs semiconductor laser. The circular pattern was first defined by electron-beam (e-beam) lithography in a layer of polymethylmethacrylate (PMMA) and subsequently etched into the semiconductor surface using chemically-assisted (chlorine) ion-beam etching (CAIBE). We consider issues that affect the fabrication and quality of the gratings. These issues include grating design requirements, data representation of the grating pattern, and e-beam scan method. We provide examples of how these techniques can be implemented and their impact on the resulting laser performance. A comparison is made of the results obtained using two fundamentally different electron-beam writing systems. Circular gratings with period lambda = 0.25 microns and overall diameters ranging from 80 microns to 500 microns were fabricated. We also report our successful demonstration of an optically pumped, concentric-circle grating, semiconductor laser that emits a beam with a far-field divergence angle that is less than one degree. The emission spectrum is quite narrow (less than 0.1 nm) and is centered at wavelength lambda = 0.8175 microns.

  9. Thermal Property Measurement of Semiconductor Melt using Modified Laser Flash Method

    NASA Technical Reports Server (NTRS)

    Lin, Bochuan; Zhu, Shen; Ban, Heng; Li, Chao; Scripa, Rosalla N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2003-01-01

    This study further developed standard laser flash method to measure multiple thermal properties of semiconductor melts. The modified method can determine thermal diffusivity, thermal conductivity, and specific heat capacity of the melt simultaneously. The transient heat transfer process in the melt and its quartz container was numerically studied in detail. A fitting procedure based on numerical simulation results and the least root-mean-square error fitting to the experimental data was used to extract the values of specific heat capacity, thermal conductivity and thermal diffusivity. This modified method is a step forward from the standard laser flash method, which is usually used to measure thermal diffusivity of solids. The result for tellurium (Te) at 873 K: specific heat capacity 300.2 Joules per kilogram K, thermal conductivity 3.50 Watts per meter K, thermal diffusivity 2.04 x 10(exp -6) square meters per second, are within the range reported in literature. The uncertainty analysis showed the quantitative effect of sample geometry, transient temperature measured, and the energy of the laser pulse.

  10. Evolution of the Novalux extended cavity surface-emitting semiconductor laser (NECSEL)

    NASA Astrophysics Data System (ADS)

    McInerney, John G.

    2016-03-01

    Novalux Inc was an enterprise founded by Aram Mooradian in 1998 to commercialise a novel electrically pumped vertical extended cavity semiconductor laser platform, initially aiming to produce pump lasers for optical fiber telecommunication networks. Following successful major investment in 2000, the company developed a range of single- and multi-mode 980 nm pump lasers emitting from 100-500 mW with excellent beam quality and efficiency. This rapid development required solution of several significant problems in chip and external cavity design, substrate and DBR mirror optimization, thermal engineering and mode selection. Output coupling to single mode fiber was exceptional. Following the collapse of the long haul telecom market in late 2001, a major reorientation of effort was undertaken, initially to develop compact 60-100 mW hybrid monolithically integrated pumplets for metro/local amplified networks, then to frequency-doubled blue light emitters for biotech, reprographics and general scientific applications. During 2001-3 I worked at Novalux on a career break from University College Cork, first as R&D Director managing a small group tasked with producing new capabilities and product options based on the NECSEL platform, including high power, pulsed and frequency doubled versions, then in 2002 as Director of New Product Realization managing the full engineering team, leading the transition to frequency doubled products.

  11. The optical effect of a semiconductor laser on protecting wheat from UV-B radiation damage.

    PubMed

    Qiu, Zong-Bo; Zhu, Xin-Jun; Li, Fang-Min; Liu, Xiao; Yue, Ming

    2007-07-01

    Lasers have been widely used in the field of biology along with the development of laser technology, but the mechanism of the bio-effect of lasers is not explicit. The objective of this paper was to test the optical effect of a laser on protecting wheat from UV-B damage. A patent instrument was employed to emit semiconductor laser (wavelength 650 nm) and incoherent red light, which was transformed from the semiconductor laser. The wavelength, power and lightfleck diameter of the incoherent red light are the same as those of the semiconductor laser. The semiconductor laser (wavelength 650 nm, power density 3.97 mW mm(-2)) and incoherent red light (wavelength 650 nm, power density 3.97 mW mm(-2)) directly irradiated the embryo of wheat seeds for 3 min respectively, and when the seedlings were 12-day-old they were irradiated by UV-B radiation (10.08 kJ m(-2)) for 12 h in the dark. Changes in the concentration of malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), glutathione (GSH), ascorbate (AsA), carotenoids (CAR), the production rate of superoxide radical (O(2)(-)), the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and the growth parameters of seedlings (plant height, leaf area and fresh weight) were measured to test the optical effect of the laser. The results showed that the incoherent red light treatment could not enhance the activities of SOD, POD and CAT and the concentration of AsA and CAR. When the plant cells were irradiated by UV-B, the incoherent red light treatment could not eliminate active oxygen and prevent lipid peroxidation in wheat. The results also clearly demonstrate that the plant DNA was damaged by UV-B radiation and semiconductor laser irradiance had the capability to protect plants from UV-B-induced DNA damage, while the incoherent red light could not. This is the first investigation reporting the optical effect of a semiconductor laser on protecting wheat from UV-B radiation damage.

  12. Diffraction-Coupled, Phase-Locked Semiconductor Laser Array

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Yariv, Amnon; Margalit, Shlomo

    1988-01-01

    Stable, narrow far field produced. Array of lasers fabricated on single chip. Individual laser waveguides isolated from each other except in end portions, where diffraction coupling takes place. Radiation pattern far from laser array has single, sharp central lobe when all lasers operate in phase with each other. Shape of lobe does not vary appreciably with array current. Applications include recording, printing, and range finding.

  13. Tolerances for Phase Locking of Semiconductor Laser Arrays.

    DTIC Science & Technology

    1988-04-18

    laser fabrication . This means that the starting material is critically important to tne success of locked laser arrays. F. TOLERANCE REQUIREMENTS ON...typically r , 0.1. Because Eq. (7) represents a small frequency deviation, and implies A - 0.5 4, this report will look into the tolerances on laser ... fabrication and operation to ensure that the free-running laser frequencies remain within this locking range. D. COMPARISON OF LOCKING CONDITION WITH

  14. Rate equations analysis of phase-locked semiconductor laser arrays under steady state conditions

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Margalit, S.; Yariv, A.

    1984-01-01

    Rate equations analysis of phase-locked semiconductor laser arrays has been carried out. It was found that for given (laser) current densities, the photon density distribution in the array elements is that particular one which maximizes the total photon density. The results of this analysis were then combined with the waveguide properties of the laser array waveguide, yielding a basic model of phase-locked diode laser arrays. This model explains the effects of the variation of the current combination through the array elements on its mode structure that were observed recently.

  15. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, R.J.; Benett, W.J.; Mills, S.T.

    1997-04-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a ``rack and stack`` configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber. 3 figs.

  16. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, Raymond J.; Benett, William J.; Mills, Steven T.

    1997-01-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a "rack and stack" configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber.

  17. Spectral characteristics of distributed feedback semiconductor laser and their improvements by corrugation-pitch-modulated structure

    NASA Astrophysics Data System (ADS)

    Okai, Makoto

    1994-01-01

    This paper presents a review of a theoretical analysis problems that occur with single-mode lasers, and a novel laser structure for superstable single-mode operation. Also presented is a new grating-fabrication technique termed photo-mask self-interference, to fabricate corrugation-pitch-modulated (CPM) structures, for enhancing the stability of the longitudinal single-mode operation in distributed feedback lasers (DFB). It is seen that the CPM-DFB laser developed for coherent transmission systems displays the narrowest spectral linewidth (56 kHz) reported so far for a semiconductor.

  18. Experimental study and chemical application of GaAs semiconductor laser treating trigeminal neuralgia

    NASA Astrophysics Data System (ADS)

    Qiu, Ke-Qum; Cao, Shu-Chen; Wang, Hu-Zhong; Wang, Ke-Ning; Xiao, Ton-Ha; Shen, Ke-Wei

    1993-03-01

    GaAs semiconductor laser was used to treat trigeminal neuralgia with an effective rate of 91.1%, and no side effects were found in 67 cases. Changes in and the recovery of the trigeminal nerve cell were studied with light and electromicroscope. Discussed in this article are the time length and quantity of laser treatment with low power. Experimental study and clinical application of the GaAs semiconductor laser have been carried out in our department since 1987. One-hundred-fifteen patients with various diseases in the maxillofacial region (including 67 cases of trigeminal neuralgia) have been treated with satisfactory effects and without any side-effects. The wavelength of the laser is 904 mu, the largest pulse length is 200 mu, and the average power is 2000 HZ.

  19. High-coherent-power, two-dimensional grating surface-emitting (GSE) semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Li, Shuang

    High-power semiconductor lasers, with coherent radiation, are attractive sources for many applications. However, achieving stable, coherent radiation to watt-range power from monolithic semiconductor lasers has been a challenge. This work covers the study and development of high power coherent semiconductor lasers employing novel-types of both surface-emitting and edge-emitting structures. Surface-emitting (SE) semiconductor lasers are preferred over edge-emitting lasers due to their inherent reliability, scalability, and packaging advantages. Horizontal-cavity, grating SE semiconductor lasers are promising candidates for high-power coherent sources. Here we present the design and analysis of a two-dimensional (2D) horizontal-cavity GSE laser (so called ROW-SEDFB laser), for which 2nd-order, distributed feedback/distributed Bragg reflector (DFB/DBR) gratings with central pi phaseshift are preferentially placed in the element regions of a resonant-optical-waveguide (ROW) structure. We find that beside their usual functions (feedback and outcoupling), the gratings act as an effective array-mode selector. The in-phase mode is strongly favored to lase around its resonance due both to better field overlap with the active-grating (i.e., DFB) and to lower interelement loss than the other array modes. For 20-element arrays with 700/600mum-long DFB/DBR gratings, and of 100mum-wide lateral dimension, high intermodal discrimination is obtained. The primary mechanisms behind this discrimination are found to be: absorption losses for the interelement field to the metal contact and to a semiconductor/metal grating layer, and the longitudinal guided-field overlap with the DFB region. The discrimination can be further enhanced by introducing free-carrier absorption in the interelement regions. The device has relatively uniform guided-field profiles in both lateral and longitudinal directions and a strong built-in index profile in the lateral direction. These features make the ROW

  20. Extraction of Semiconductor Microchip Differential Gain by Use of Optically Pumped Semiconductor Laser (POSTPRINT)

    DTIC Science & Technology

    2009-09-01

    intracavity filter- ing elements. The VECSEL chip is pumped with two 808 nm lasers . First, a high - power fiber-coupled laser bar imaged onto the...received considerable attention. In the past decade, VECSELs have been investigated for their high power , high efficiency, ability to operate in con... power ridge laser is biased above threshold and is sinusoidally modulated with an amplitude of approximately 18 W. This second ac pump is imaged

  1. Simple laser velocimeter that uses photoconductive semiconductors to measure optical frequency differences.

    PubMed

    Wang, C C; Davidson, F; Trivedi, S

    1995-10-01

    The dc photocurrents generated by steady-state moving space-charge fields inside photoconductive semiconductors containing deep level donors and traps can be used to determine the relative frequency differences between the two interfering optical fields that establish the space-charge fields. A simple laser velocimeter that uses a semi-insulating GaAs:Cr sample to detect the Doppler frequency shift between two laser beams is demonstrated.

  2. Dynamical Slowing and trapping of light in coupled semiconductor laser arrays.

    PubMed

    Yifat, Yuval; Scheuer, Jacob

    2009-09-28

    We propose and analyze a new scheme for storing and releasing optical pulses comprising an array of weakly coupled semiconductor lasers. By activating and deactivating individual lasers in the array we are able to manipulate optical pulses, trap them for long periods and release them without noticeable distortion. In addition, the proposed scheme can also regenerate and reshape distorted pulses all-optically. Additional applications such as routing, pulse synchronization and true-time-delaying are also presented and discussed.

  3. GaAs/GaInP double heterostructure characterization for laser cooling of semiconductors

    NASA Astrophysics Data System (ADS)

    Wang, Chengao; Li, Chia-Yeh; Hasselbeck, Michael P.; Rotter, Thomas; Malloy, Kevin; Sheik-Bahae, Mansoor; Olson, Jerry

    2011-03-01

    External quantum efficiency of semiconductor photonic devices is directly measured by wavelength-dependent laser-induced temperature change (scanning laser calorimetry) with very high accuracy. Maximum efficiency is attained at an optimum photo-excitation level that can be determined with an independent measurement of power-dependent photoluminescence. Differential power-dependent photoluminescence measurement is used to quickly screen the sample quality before processing.

  4. Saturated semiconductor optical amplifier phase modulation for long range laser radar applications.

    PubMed

    Carns, Jennifer L; Duncan, Bradley D; Dierking, Matthew P

    2012-08-20

    We investigate the use of a semiconductor optical amplifier operated in the saturation regime as a phase modulator for long range laser radar applications. The nature of the phase and amplitude modulation resulting from a high peak power Gaussian pulse, and the impact this has on the ideal pulse response of a laser radar system, is explored. We also present results of a proof-of-concept laboratory demonstration using phase-modulated pulses to interrogate a stationary target.

  5. Electrically pumped semiconductor laser with monolithic control of circular polarization

    PubMed Central

    Rauter, Patrick; Lin, Jiao; Genevet, Patrice; Khanna, Suraj P.; Lachab, Mohammad; Giles Davies, A.; Linfield, Edmund H.; Capasso, Federico

    2014-01-01

    We demonstrate surface emission of terahertz (THz) frequency radiation from a monolithic quantum cascade laser with built-in control over the degree of circular polarization by “fishbone” gratings composed of orthogonally oriented aperture antennas. Different grating concepts for circularly polarized emission are introduced along with the presentation of simulations and experimental results. Fifth-order gratings achieve a degree of circular polarization of up to 86% within a 12°-wide core region of their emission lobes in the far field. For devices based on an alternative transverse grating design, degrees of circular polarization as high as 98% are demonstrated for selected far-field regions of the outcoupled THz radiation and within a collection half-angle of about 6°. Potential and limitations of integrated antenna gratings for polarization-controlled emission are discussed. PMID:25512515

  6. Electrically pumped semiconductor laser with monolithic control of circular polarization.

    PubMed

    Rauter, Patrick; Lin, Jiao; Genevet, Patrice; Khanna, Suraj P; Lachab, Mohammad; Giles Davies, A; Linfield, Edmund H; Capasso, Federico

    2014-12-30

    We demonstrate surface emission of terahertz (THz) frequency radiation from a monolithic quantum cascade laser with built-in control over the degree of circular polarization by "fishbone" gratings composed of orthogonally oriented aperture antennas. Different grating concepts for circularly polarized emission are introduced along with the presentation of simulations and experimental results. Fifth-order gratings achieve a degree of circular polarization of up to 86% within a 12°-wide core region of their emission lobes in the far field. For devices based on an alternative transverse grating design, degrees of circular polarization as high as 98% are demonstrated for selected far-field regions of the outcoupled THz radiation and within a collection half-angle of about 6°. Potential and limitations of integrated antenna gratings for polarization-controlled emission are discussed.

  7. Thiazole-based organic semiconductors for organic electronics.

    PubMed

    Lin, Yuze; Fan, Haijun; Li, Yongfang; Zhan, Xiaowei

    2012-06-19

    Over the past two decades, organic semiconductors have been the subject of intensive academic and commercial interests. Thiazole is a common electron-accepting heterocycle due to electron-withdrawing nitrogen of imine (C=N), several moieties based on thiazole have been widely introduced into organic semiconductors, and yielded high performance in organic electronic devices. This article reviews recent developments in the area of thiazole-based organic semiconductors, particularly thiazole, bithiazole, thiazolothiazole and benzobisthiazole-based small molecules and polymers, for applications in organic field-effect transistors, solar cells and light-emitting diodes. The remaining problems and challenges, and the key research direction in near future are discussed.

  8. Welding of Semiconductor Nanowires by Coupling Laser-Induced Peening and Localized Heating

    PubMed Central

    Rickey, Kelly M.; Nian, Qiong; Zhang, Genqiang; Chen, Liangliang; Suslov, Sergey; Bhat, S. Venkataprasad; Wu, Yue; Cheng, Gary J.; Ruan, Xiulin

    2015-01-01

    We demonstrate that laser peening coupled with sintering of CdTe nanowire films substantially enhances film quality and charge transfer while largely maintaining basic particle morphology. During the laser peening phase, a shockwave is used to compress the film. Laser sintering comprises the second step, where a nanosecond pulse laser beam welds the nanowires. Microstructure, morphology, material content, and electrical conductivities of the films are characterized before and after treatment. The morphology results show that laser peening can decrease porosity and bring nanowires into contact, and pulsed laser heating fuses those contacts. Multiphysics simulations coupling electromagnetic and heat transfer modules demonstrate that during pulsed laser heating, local EM field enhancement is generated specifically around the contact areas between two semiconductor nanowires, indicating localized heating. The characterization results indicate that solely laser peening or sintering can only moderately improve the thin film quality; however, when coupled together as laser peen sintering (LPS), the electrical conductivity enhancement is dramatic. LPS can decrease resistivity up to a factor of ~10,000, resulting in values on the order of ~105 Ω-cm in some cases, which is comparable to CdTe thin films. Our work demonstrates that LPS is an effective processing method to obtain high-quality semiconductor nanocrystal films. PMID:26527570

  9. Biological semiconductor based on electrical percolation.

    PubMed

    Yang, Minghui; Bruck, Hugh Alan; Kostov, Yordan; Rasooly, Avraham

    2010-05-01

    We have developed a novel biological semiconductor (BSC) based on electrical percolation through a multilayer three-dimensional carbon nanotube-antibody bionanocomposite network, which can measure biological interactions directly and electronically. In electrical percolation, the passage of current through the conductive network is dependent upon the continuity of the network. Molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. A BSC is fabricated by immobilizing a prefunctionalized single-walled carbon nanotubes (SWNTs)-antibody bionanocomposite directly on a poly(methyl methacrylate) (PMMA) surface (also known as plexiglass or acrylic). We used the BSC for direct (label-free) electronic measurements of antibody-antigen binding, showing that, at slightly above the electrical percolation threshold of the network, binding of a specific antigen dramatically increases the electrical resistance. Using anti-staphylococcal enterotoxin B (SEB) IgG as a "gate" and SEB as an "actuator", we demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/mL. The new BSCs may permit assembly of multiple sensors on the same chip to create "biological central processing units (CPUs)" with multiple BSC elements, capable of processing and sorting out information on multiple analytes simultaneously.

  10. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking

    PubMed Central

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J.; Grillot, Frédéric

    2016-01-01

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%. PMID:27302301

  11. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  12. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking.

    PubMed

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J; Grillot, Frédéric

    2016-06-15

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%.

  13. Laser Spectroscopy of Small Metal and Semiconductor Molecules

    NASA Astrophysics Data System (ADS)

    Winstead, Christopher Brooks

    1995-01-01

    An apparatus consisting of a laser vaporization cluster source coupled to a time-of-flight mass spectrometer has been implemented to facilitate the mass-selected spectroscopy of small silver and silicon molecules. Resonantly enhanced multiphoton ionization (REMPI) studies have revealed a previously unknown silver dimer excited electronic state via a forbidden transition near 46870 cm^ {-1}. This state lies in near perfect double resonance with the lower energy A ^1 Sigma_sp{rm u}{+}( rm v^' = 3) >= X ^Sigma_sp{rm g}{+}({rm v^{' '}} = 0) transition, leading to an anomalously large single color Ag_2 ionization signal near 426.7 nm. Symmetry selection rules allow an identification of the new state symmetry as 1_{rm g} or 0 _sp{rm g}{+}. Additional REMPI investigations of the A ^1Sigma _sp{rm u}{+} >=ts X ^1Sigma_sp {rm g}{+} transition yield a new measurement of the Ag_2 ionization potential (IP) and resolve a discrepancy in the reported Ag_2 IP values. The importance of field ionization effects on the observed REMPI spectra is also demonstrated. The spectroscopy of the H ^3Sigma _sp{rm u}{-} state of silicon dimer has been investigated using a combination of laser induced fluorescence and resonant two-photon ionization techniques. Measurements of the isotope induced bandhead shifts for the Si_2 H ^3 Sigma_sp{rm u}{-} >=ts X ^3Sigma_sp {rm g}{-} transition reveal that the previously accepted vibrational numbering of the H ^3Sigma_sp{rm u}{-} state is incorrect. Revised molecular constants based on the new vibrational numbering scheme are T_{rm e} = 24151.86 cm^{-1}, omega_{rm e} = 279.28 cm^{-1}, omega _{rm e}chi_{rm e} = 1.99 cm^{-1} , B_{rm e} = 0.17255 cm^{-1}, and alpha_{rm e} = 0.00135 cm^{-1}. A comparison of experimentally obtained and simulated dispersed laser induced fluorescence spectra demonstrates the improved accuracy of these new constants. Resonant two-photon ionization studies of the H ^3Sigma_sp {rm u}{-} state have also allowed the most accurate

  14. Field performance of an all-semiconductor laser coherent Doppler lidar.

    PubMed

    Rodrigo, Peter John; Pedersen, Christian

    2012-06-15

    We implement and test what, to our knowledge, is the first deployable coherent Doppler lidar (CDL) system based on a compact, inexpensive all-semiconductor laser (SL). To demonstrate the field performance of our SL-CDL remote sensor, we compare a 36 h time series of averaged radial wind speeds measured by our instrument at an 80 m distance to those simultaneously obtained from an industry-standard sonic anemometer (SA). An excellent degree of correlation (R2=0.994 and slope=0.996) is achieved from a linear regression analysis of the CDL versus SA wind speed data. The lidar system is capable of providing high data availability, ranging from 85% to 100% even under varying outdoor (temperature and humidity) conditions during the test period. We also show the use of our SL-CDL for monitoring the dependence of aerosol backscatter on relative humidity. This work points to the feasibility of a more general class of low-cost, portable remote sensors based on all-SL emitters for applications that require demanding laser stability and coherence.

  15. Direct laser writing of topographic features in semiconductor-doped glass

    NASA Astrophysics Data System (ADS)

    Smuk, Andrei Y.

    2000-11-01

    Patterning of glass and silica surfaces is important for a number of modern technologies, which depend on these materials for manufacturing of both final products, such as optics, and prototypes for casting and molding. Among the fields that require glass processing on microscopic scale are optics (lenses and arrays, diffractive/holographic elements, waveguides), biotechnology (capillary electrophoresis chips and biochemical libraries) and magnetic media (landing zones for magnetic heads). Currently, standard non-laser techniques for glass surface patterning require complex multi-step processes, such as photolithography. Work carried out at Brown has shown that semiconductor- doped glasses (SDG) allow a single-step patterning process using low power continuous-wave visible lasers. SDG are composite materials, which consist of semiconductor crystallites embedded into glass matrix. In this study, borosilicate glasses doped with CdSxSe1-x nanocrystals were used. Exposure of these materials to a low-power above- the-energy gap laser beam leads to local softening, and subsequent expansion and rapid solidification of the exposed volume, resulting in a nearly spherical topographic feature on the surface. The effects of the incident power, beam configuration, and the exposure time on the formation and final parameters of the microlens were studied. Based on the numerical simulation of the temperature distribution produced by the absorbed Gaussian beam, and the ideas of viscous flow at the temperatures around the glass transition point, a model of lens formation is suggested. The light intensity distribution in the near-field of the growing lens is shown to have a significant effect on the final lens height. Fabrication of dense arrays of microlenses is shown, and the thermal and structural interactions between the neighboring lenses were also studied. Two-dimensional continuous-profile topographic features are achieved by exposure of the moving substrates to the writing

  16. Semiconductor photoelectrochemistry

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.; Byvik, C. E.

    1983-01-01

    Semiconductor photoelectrochemical reactions are investigated. A model of the charge transport processes in the semiconductor, based on semiconductor device theory, is presented. It incorporates the nonlinear processes characterizing the diffusion and reaction of charge carriers in the semiconductor. The model is used to study conditions limiting useful energy conversion, specifically the saturation of current flow due to high light intensity. Numerical results describing charge distributions in the semiconductor and its effects on the electrolyte are obtained. Experimental results include: an estimate rate at which a semiconductor photoelectrode is capable of converting electromagnetic energy into chemical energy; the effect of cell temperature on the efficiency; a method for determining the point of zero zeta potential for macroscopic semiconductor samples; a technique using platinized titanium dioxide powders and ultraviolet radiation to produce chlorine, bromine, and iodine from solutions containing their respective ions; the photoelectrochemical properties of a class of layered compounds called transition metal thiophosphates; and a technique used to produce high conversion efficiency from laser radiation to chemical energy.

  17. Dual-comb modelocked lasers: semiconductor saturable absorber mirror decouples noise stabilization.

    PubMed

    Link, Sandro M; Klenner, Alexander; Keller, Ursula

    2016-02-08

    In this paper we present the stabilization of the pulse repetition rate of dual-comb lasers using an intracavity semiconductor saturable absorber mirror (SESAM) for passive modelocking and an intracavity birefringent crystal for polarization-duplexing to obtain simultaneous emission of two modelocked beams from the same linear cavity sharing all components. Initially surprising was the observation that the cavity length adjustments to stabilize one polarization did not significantly affect the pulse repetition rate of the other. We gained insight in the underlying physics using both a semiconductor and Nd:YAG laser gain material with the conclusion that the pulse arrival timing jitter of the two beams is decoupled by the uncorrelated time delay from the saturated SESAM and becomes locked with sufficient but not too much pulse overlap. Noise stabilization is in all cases still possible for both combs. The dual-comb modelocked laser is particularly interesting for the semiconductor laser enabling the integration of gain and absorber layers within one wafer (referred to as the modelocked integrated external-cavity surface emitting laser--MIXSEL).

  18. Quantifying complexity of the chaotic regime of a semiconductor laser subject to feedback via information theory measures

    NASA Astrophysics Data System (ADS)

    Soriano, Miguel C.; Zunino, Luciano; Rosso, Osvaldo A.; Mirasso, Claudio R.

    2010-04-01

    The time evolution of the output of a semiconductor laser subject to optical feedback can exhibit high-dimensional chaotic fluctuations. In this contribution, our aim is to quantify the complexity of the chaotic time-trace generated by a semiconductor laser subject to delayed optical feedback. To that end, we discuss the properties of two recently introduced complexity measures based on information theory, namely the permutation entropy (PE) and the statistical complexity measure (SCM). The PE and SCM are defined as a functional of a symbolic probability distribution, evaluated using the Bandt-Pompe recipe to assign a probability distribution function to the time series generated by the chaotic system. In order to evaluate the performance of these novel complexity quantifiers, we compare them to a more standard chaos quantifier, namely the Kolmogorov-Sinai entropy. Here, we present numerical results showing that the statistical complexity and the permutation entropy, evaluated at the different time-scales involved in the chaotic regime of the laser subject to optical feedback, give valuable information about the complexity of the laser dynamics.

  19. Comparison of the coherence properties of superradiance and laser emission in semiconductor structures

    SciTech Connect

    Vasil'ev, Petr P; Penty, R V; White, I H

    2012-12-31

    The coherence properties of a transient electron - hole state developing during superradiance emission in semiconductor laser structures have been studied experimentally using a Michelson interferometer and Young's classic double-slit configuration. The results demonstrate that, in the lasers studied, the first-order correlation function, which quantifies spatial coherence, approaches unity for superradiant emission and is 0.2 - 0.5 for laser emission. The supercoherence is due to long-range ordering upon the superradiant phase transition. (special issue devoted to the 90th anniversary of n.g. basov)

  20. Preliminary study on weight reduction of obesity Patients with semiconductor laser acupuncture

    NASA Astrophysics Data System (ADS)

    Cao, Chun; Wang, Jannan; Liao, Jianghong; Zhang, Jinghe; Qiao, Yongfan; Liu, Jindong; Liu, Jun-Qi; Lu, Zhenwu

    1998-08-01

    To study the effects of the laser on simple obesity (SO), 40 cases of SO patients, which was treated with Semiconductor Laser Acupuncture (SLA), were observed. The treatment Results: the obvious effect were 19 cases (47.5%), the effect 19(47.5%) and no effect 2(5%), so the total effect reached to 95% (P less than 0.01). No any side affection has been observed, and it is suggested that the Laser beam on acupoint can regulate the function of endocrine why the obesity happens.

  1. Consistency Properties of a Chaotic Semiconductor Laser Driven by Optical Feedback

    NASA Astrophysics Data System (ADS)

    Oliver, Neus; Jüngling, Thomas; Fischer, Ingo

    2015-03-01

    We experimentally study consistency properties of a semiconductor laser in response to a coherent optical drive originating from delayed feedback. The laser is connected to a short and a long optical fiber loop, switched such that only one is providing input to the laser at a time. This way, repeating the exact same optical drive twice, we find consistent or inconsistent responses depending on the pump parameter and we relate the kind of response to strong and weak chaos. Moreover, we are able to experimentally determine the sub-Lyapunov exponent, underlying the consistency properties.

  2. Experimental study on apoptosis induced by semiconductor laser to hair removal and armpit odor treatment

    NASA Astrophysics Data System (ADS)

    Shi, Hongmin; Yan, Min; Zhang, Meijue

    2005-07-01

    Objective: To observe and explore the effects and mechanism of apoptosis on canine induced by Laser. Try to find a new approach to treat of armpit odor with no traumatism. Method: We used different power of semiconductor Laser to irradiate the black hair canine to observe and evaluate the tissue effects with electroscope, flow cytometry and Tunel technique at different period of time after irradiation. Result: The apoptosis has been observed within the hair follicle cells and apocrine gland cells after irradiation. After repeat irradiation in low power level, more apoptosis has been observed. Conclusion: Apoptosis exists in hair follicle cells and apocrine gland cells after Laser irradiation.

  3. Simulation of spectral stabilization of high-power broad-area edge emitting semiconductor lasers.

    PubMed

    Holly, Carlo; Hengesbach, Stefan; Traub, Martin; Hoffmann, Dieter

    2013-07-01

    The simulation of spectral stabilization of broad-area edge-emitting semiconductor diode lasers is presented in this paper. In the reported model light-, temperature- and charge carrier-distributions are solved iteratively in frequency domain for transverse slices along the semiconductor heterostructure using wide-angle finite-difference beam propagation. Depending on the operating current the laser characteristics are evaluated numerically, including near- and far-field patterns of the astigmatic laser beam, optical output power and the emission spectra, with central wavelength and spectral width. The focus of the model lies on the prediction of influences on the spectrum and power characteristics by frequency selective feedback from external optical resonators. Results for the free running and the spectrally stabilized diode are presented.

  4. Analysis of the effects of periodic forcing in the spike rate and spike correlation's in semiconductor lasers with optical feedback

    NASA Astrophysics Data System (ADS)

    Quintero-Quiroz, C.; Sorrentino, Taciano; Torrent, M. C.; Masoller, Cristina

    2016-04-01

    We study the dynamics of semiconductor lasers with optical feedback and direct current modulation, operating in the regime of low frequency fluctuations (LFFs). In the LFF regime the laser intensity displays abrupt spikes: the intensity drops to zero and then gradually recovers. We focus on the inter-spike-intervals (ISIs) and use a method of symbolic time-series analysis, which is based on computing the probabilities of symbolic patterns. We show that the variation of the probabilities of the symbols with the modulation frequency and with the intrinsic spike rate of the laser allows to identify different regimes of noisy locking. Simulations of the Lang-Kobayashi model are in good qualitative agreement with experimental observations.

  5. Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

    PubMed Central

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-01-01

    A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

  6. Semiconductor nanostructure-based photovoltaic solar cells.

    PubMed

    Zhang, Genqiang; Finefrock, Scott; Liang, Daxin; Yadav, Gautam G; Yang, Haoran; Fang, Haiyu; Wu, Yue

    2011-06-01

    Substantial efforts have been devoted to design, synthesize, and integrate various semiconductor nanostructures for photovoltaic (PV) solar cells. In this article, we will review the recent progress in this exciting area and cover the material chemistry and physics related to all-inorganic nanostructure solar cells, hybrid inorganic nanostructure-conductive polymer composite solar cells, and dye-sensitized solar cells.

  7. Semiconductor nanostructure-based photovoltaic solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Genqiang; Finefrock, Scott; Liang, Daxin; Yadav, Gautam G.; Yang, Haoran; Fang, Haiyu; Wu, Yue

    2011-06-01

    Substantial efforts have been devoted to design, synthesize, and integrate various semiconductor nanostructures for photovoltaic (PV) solar cells. In this article, we will review the recent progress in this exciting area and cover the material chemistry and physics related to all-inorganic nanostructure solar cells, hybrid inorganic nanostructure-conductive polymer composite solar cells, and dye-sensitized solar cells.

  8. Laser writing of semiconductor nanoparticles and quantum dots

    SciTech Connect

    Bertino, M.F.; Gadipalli, R.R.; Story, J.G.; Williams, C.G.; Zhang, G.; Sotiriou-Leventis, C.; Tokuhiro, A.T.; Guha, S.; Leventis, N.

    2004-12-13

    Silica aerogels were patterned with CdS using a photolithographic technique based on local heating with infrared (IR) light. The solvent of silica hydrogels was exchanged with an aqueous solution of the precursors CdNO{sub 3} and NH{sub 4}OH, all precooled to a temperature of 5 deg. C. Half of the bathing solution was then replaced by a thiourea solution. After thiourea diffused into the hydrogels, the samples were exposed to a focused IR beam from a continuous wave, Nd-YAG laser. The precursors reacted in the spots heated by the IR beam to form CdS nanoparticles. We lithographed features with a diameter of about 40 {mu}m, which extended inside the monoliths for up to 4 mm. Samples were characterized with transmission electron microscopy and optical absorption, photoluminescence, and Raman spectroscopies. Spots illuminated by the IR beam were made up by CdS nanoparticles dispersed in a silica matrix. The CdS nanoparticles had a diameter in the 4-6 nm range in samples exposed for 4 min to the IR beam, and of up to 100 nm in samples exposed for 10 min.

  9. Method and Apparatus for Linewidth Reduction in Distributed Feedback or Distributed Bragg Reflector Semiconductor Lasers using Vertical Emission

    NASA Technical Reports Server (NTRS)

    Cook, Anthony L. (Inventor); Hendricks, Herbert D. (Inventor)

    1998-01-01

    The linewidth of a distributed feedback semiconductor laser or a distributed Bragg reflector laser having one or more second order gratings is reduced by using an external cavity to couple the vertical emission back into the laser. This method and device prevent disturbance of the main laser beam. provide unobstructed access to laser emission for the formation of the external cavity. and do not require a very narrow heat sink. Any distributed Bragg reflector semiconductor laser or distributed feedback semiconductor laser that can produce a vertical emission through the epitaxial material and through a window in the top metallization can be used. The external cavity can be formed with an optical fiber or with a lens and a mirror of grating.

  10. A semiconductor injection-switched high-pressure sub-10-picosecond carbon dioxide laser amplifier

    NASA Astrophysics Data System (ADS)

    Hughes, Michael Kon Yew

    A multiatmospheric-pressure-broadened CO2 laser amplifier was constructed to amplify sub-10-picosecond pulses generated with semiconductor switching. High-intensity, mid-infrared, amplified pulses have many applications: especially in fields such as non-linear optics, laser-plasma interaction, and laser particle acceleration. The injected pulses are produced by exciting GaAs (or an engineered, fast-recombination time semiconductor) with an ultrafast visible laser pulse to induce transient free carriers with sufficient density to reflect a co-incident hybrid-CO2 laser pulse. The short pulse is injected directly into the regenerative amplifier cavity from an intra-cavity semiconductor switch. The CO2-gas-mix amplifier is operated at 1.24 MPa which is sufficient to collisionally broaden the individual rotational spectral lines so that they merge to produce a gain spectrum wide enough to support pulses less than 10 ps long. After sufficient amplification, the pulse is switched out with another semiconductor switch pumped with a synchronized visible-laser pulse. This system is demonstrated and analysed spectrally and temporally. The pulse-train spectral analysis is done for a GaAs-GaAs double-switch arrangement using a standard spectrometer and two HgCdTe detectors; one of which is used for a reference signal. An infrared autocorrelator was designed and constructed to temporally analyse the pulse trains emerging from the amplifier. Interpretation of the results was aided by the development of a computer model for short-pulse amplification which incorporated saturation effects, rotational- and vibrational-mode energy redistribution between pulse round trips, and the gain enhancement due to one sequence band. The results show that a sub-10-picosecond pulse is injected into the cavity and that it is amplified with some trailing pulses at 18 ps intervals generated by coherent effects. The energy level reached, estimated through modelling, was >100 mJ/cm2.

  11. Static and Dynamic Effects of Lateral Carrier Diffusion in Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Li, Jian-Zhong; Cheung, Samson H.; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Electron and hole diffusions in the plane of semiconductor quantum wells play an important part in the static and dynamic operations of semiconductor lasers. It is well known that the value of diffusion coefficients affects the threshold pumping current of a semiconductor laser. At the same time, the strength of carrier diffusion process is expected to affect the modulation bandwidth of an AC-modulated laser. It is important not only to investigate the combined DC and AC effects due to carrier diffusion, but also to separate the AC effects from that of the combined effects in order to provide design insights for high speed modulation. In this presentation, we apply a hydrodynamic model developed by the present authors recently from the semiconductor Bloch equations. The model allows microscopic calculation of the lateral carrier diffusion coefficient, which is a nonlinear function of the carrier density and plasma temperature. We first studied combined AC and DC effects of lateral carrier diffusion by studying the bandwidth dependence on diffusion coefficient at a given DC current under small signal modulation. The results show an increase of modulation bandwidth with decrease in the diffusion coefficient. We simultaneously studied the effects of nonlinearity in the diffusion coefficient. To clearly identify how much of the bandwidth increase is a result of decrease in the threshold pumping current for smaller diffusion coefficient, thus an effective increase of DC pumping, we study the bandwidth dependence on diffusion coefficient at a given relative pumping. A detailed comparison of the two cases will be presented.

  12. Gallium Arsenide Semiconductor-Laser Multigas Analyzer (GASMAN).

    DTIC Science & Technology

    1996-09-01

    a single - board computer as a digital signal processor. The concentration values are stored in the on-board flash memory, displayed on an LCD, and... board computer (SBC) allows the development of simple software upgrades for GASMAN. The next-generation laser diode driver currently being developed...higher sensitivity. Modules that can be built using available lasers are listed in Table 4. 4.2 Software Upgrade The use of C source code and a single

  13. Incoherent GaAlAs/GaAs semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Hwang, C. J.; Chen, J. S.; Fu, R. J.; Wu, D. H.; Wang, C. S.

    1988-01-01

    The fabrication of an incoherent laser array is reported. The main features of the arrays are low threshold index-guided laser elements, single-lobe far-field pattern, low astigmatism, low current operation, dense packing, and total electrical and optical isolation. With further development, this device should have applications in multihead optical-disk reading and writing, multifiber optical communications, and line-of-sight communications.

  14. Femtosecond laser-induced formation of submicrometer spikes on a semiconductor substrate

    DOEpatents

    Mazur, Eric , Shen; Mengyan

    2011-02-08

    The present invention generally provides semiconductor substrates having submicron-sized surface features generated by irradiating the surface with ultra short laser pulses. In one aspect, a method of processing a semiconductor substrate is disclosed that includes placing at least a portion of a surface of the substrate in contact with a fluid, and exposing that surface portion to one or more femtosecond pulses so as to modify the topography of that portion. The modification can include, e.g., generating a plurality of submicron-sized spikes in an upper layer of the surface.

  15. Femtosecond laser-induced formation of submicrometer spikes on a semiconductor substrate

    DOEpatents

    Mazur, Eric; Shen, Mengyan

    2008-10-28

    The present invention generally provides semiconductor substrates having submicron-sized surface features generated by irradiating the surface with ultra short laser pulses. In one aspect, a method of processing a semiconductor substrate is disclosed that includes placing at least a portion of a surface of the substrate in contact with a fluid, and exposing that surface portion to one or more femtosecond pulses so as to modify the topography of that portion. The modification can include, e.g., generating a plurality of submicron-sized spikes in an upper layer of the surface.

  16. All quantum dot mode-locked semiconductor disk laser emitting at 655 nm

    SciTech Connect

    Bek, R. Kersteen, G.; Kahle, H.; Schwarzbäck, T.; Jetter, M.; Michler, P.

    2014-08-25

    We present a semiconductor disk laser mode-locked by a semiconductor saturable absorber mirror (SESAM) with emission in the red spectral range. Both the gain and the absorber structure are fabricated by metal-organic vapor-phase epitaxy in an anti-resonant design using quantum dots as active material. A v-shaped cavity is used to tightly focus onto the SESAM, producing pulses with a duration of about 1 ps at a repetition rate of 852 MHz.

  17. Femtosecond laser-induced formation of submicrometer spikes on a semiconductor substrate

    DOEpatents

    Mazur, Eric; Shen, Mengyan

    2015-09-15

    The present invention generally provides semiconductor substrates having submicronsized surface features generated by irradiating the surface with ultra short laser pulses. In one aspect, a method of processing a semiconductor substrate is disclosed that includes placing at least a portion of a surface of the substrate in contact with a fluid, and exposing that surface portion to one or more femtosecond pulses so as to modify the topography of that portion. The modification can include, e.g., generating a plurality of submicron-sized spikes in an upper layer of the surface.

  18. Femtosecond laser-induced formation of submicrometer spikes on a semiconductor substrate

    DOEpatents

    Mazur, Eric; Shen, Mengyan

    2013-12-03

    The present invention generally provides a semiconductor substrates having submicron-sized surface features generated by irradiating the surface with ultra short laser pulses. In one aspect, a method of processing a semiconductor substrate is disclosed that includes placing at least a portion of a surface of the substrate in contact with a fluid, and exposing that surface portion to one or more femtosecond pulses so as to modify the topography of that portion. The modification can include, e.g., generating a plurality of submicron-sized spikes in an upper layer of the surface.

  19. A study on the reliability of indium solder die bonding of high power semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Liu, Xingsheng; Davis, Ronald W.; Hughes, Lawrence C.; Rasmussen, Michael H.; Bhat, Rajaram; Zah, Chung-En; Stradling, Jim

    2006-07-01

    High power semiconductor lasers have found increased applications. Indium solder is one of the most widely used solders in high power laser die bonding. Indium solder has some advantages in laser die bonding. It also has some concerns, however, especially in terms of reliability. In this paper, the reliability of indium solder die bonding of high power broad area semiconductor lasers was studied. It was found that indium solder bonded lasers have much shorter lifetime than AuSn solder bonded devices. Catastrophic degradation was observed in indium solder bonded lasers. Nondestructive optical and acoustic microscopy was conducted during the lifetime testing to monitor the failure process and destructive failure analysis was performed after the lasers failed. It was found that the sudden failure was caused by electromigration of indium solder at the high testing current of up to 7A. It was shown that voids were created and gradually enlarged by indium solder electromigration, which caused local heating near the facets of the laser. The local heating induced catastrophic optical mirror damage (COMD) of the lasers. It was discussed that current crowding, localized high temperature, and large temperature gradient contributed to the fast indium solder electromigration. It was observed that some bright pattern structures appeared on the front facet of the indium solder bonded lasers after the devices failed and the bright patterns grew and spread upon further testing. Failure analysis showed that the bright pattern structure apparent on the front facet was due to crystallization of the TiOx material of the front facet coating as a result of overheating during lifetime testing. It was concluded that indium solder is not suitable for high power laser applications due to electromigration at high current densities and high temperatures.

  20. Range-resolved gas concentration measurements using tunable semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Lytkine, A.; Lau, B.; Lim, A.; Jäger, W.; Tulip, J.

    2008-02-01

    A method for range-resolved gas sensing using path-integrated optical systems is presented. The method involves dividing an absorption path into several measurement segments and extracting the gas concentration in each segment from two path-integrated measurements. We implemented the method with tunable lasers (a 1389-nm VCSEL and a 10.9-μm pulsed quantum cascade laser) and a group of retro reflectors (RRs) distributed along absorption paths. Using a rotating mirror with the VCSEL configuration, we could scan a group of seven tape RRs spaced by 10 cm in ˜ 9 ms to extract an H2O concentration profile. Reduced H2O concentrations were recorded in the segments purged with dry air. Hollow corner cube RRs were used in the quantum cascade laser configuration at distances up to 1.1 km from the laser. Two RRs placed at 66 m and 125 m from the laser allowed us to determine H2O concentrations in both segments. The RRs returns were separated due to the different round trip travel time of the 200-ns laser pulse. Novel instruments for range-resolved remote sensing in the atmosphere can be developed for a variety of applications, including monitoring the fluxes of atmospheric pollutants and controlling air quality in populated areas.

  1. Quantum coherence in semiconductor nanostructures for improved lasers and detectors.

    SciTech Connect

    Chow, Weng Wah Dr.; Lyo, Sungkwun Kenneth; Cederberg, Jeffrey George; Modine, Normand Arthur; Biefeld, Robert Malcolm

    2006-02-01

    The potential for implementing quantum coherence in semiconductor self-assembled quantum dots has been investigated theoretically and experimentally. Theoretical modeling suggests that coherent dynamics should be possible in self-assembled quantum dots. Our experimental efforts have optimized InGaAs and InAs self-assembled quantum dots on GaAs for demonstrating coherent phenomena. Optical investigations have indicated the appropriate geometries for observing quantum coherence and the type of experiments for observing quantum coherence have been outlined. The optical investigation targeted electromagnetically induced transparency (EIT) in order to demonstrate an all optical delay line.

  2. Apertureless scanning microscope probe as a detector of semiconductor laser emission

    SciTech Connect

    Dunaevskiy, Mikhail; Dontsov, Anton; Monakhov, Andrei; Alekseev, Prokhor; Titkov, Alexander; Baranov, Alexei; Girard, Paul; Arinero, Richard; Teissier, Roland

    2015-04-27

    An operating semiconductor laser has been studied using a scanning probe microscope. A shift of the resonance frequency of probe that is due to its heating by laser radiation has been analyzed. The observed shift is proportional to the absorbed radiation and can be used to measure the laser near field or its output power. A periodical dependence of the measured signal has been observed as a function of distance between the probe and the surface of the laser due to the interference of the outgoing and cantilever-reflected waves. Due to the multiple reflections resulting in the interference, the light absorption by the probe cantilever is greatly enhanced compared with a single pass case. Interaction of infrared emission of a diode laser with different probes has been studied.

  3. Development and performance of a laser heterodyne spectrometer using tunable semiconductor lasers as local oscillators

    NASA Technical Reports Server (NTRS)

    Glenar, D.; Kostiuk, T.; Jennings, D. E.; Mumma, M. J.

    1980-01-01

    A diode laser based IR heterodyne spectrometer for laboratory and field use was developed for high efficiency operation between 7.5 and 8.5 microns. The local oscillator is a PbSSe tunable diode laser kept continuously at operating temperatures of 12-60 K using a closed cycle cooler. The laser output frequency is controlled and stabilized using a high precision diode current supply, constant temperature controller, and a shock isolator mounted between the refrigerator cold tip and the diode mount. Single laser modes are selected by a grating placed in the local oscillator beam. The system employs reflecting optics throughout to minimize losses from internal reflection and absorption, and to eliminate chromatic effects. Spectral analysis of the diode laser output between 0 and 1 GHz reveals excess noise at many diode current settings, which limits the infrared spectral regions over which useful heterodyne operation can be achieved. System performance has been studied by making heterodyne measurements of etalon fringes and several Freon 13 (CF3Cl) absorption lines against a laboratory blackbody source. Preliminary field tests have also been performed using the Sun as a source.

  4. Laser-dressing of electronic quantum states in graded semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Radu, A.

    2013-03-01

    It is known that a non-resonant laser field will modify the electronic states in a low-dimensional semiconductor very similarly to the laser-dressing of electrons in isolate atoms. Under intense laser field, the energy levels are functions of the laser parameter which depends on the intensity and frequency of the laser but also on the effective mass of the carriers. This aspect is qualitatively different as compared with the laser-dressing of atoms and it was poorly addressed in the literature until now. This work will demonstrate that in compositionally graded quantum wells the gradient of the effective mass will affect the laser dressing of electronic states in a non-trivial manner. The operatorial nature of the laser parameter leads to a surprising result: the electrons in different subbands will feel different laser-dressed confinement potentials. In particular, for a non-graded quantum well the expectation value of the laser parameter will depend on the effective masses of the electron in all distinct layers of the heterostructure.

  5. Doped semiconductor nanocrystal based fluorescent cellular imaging probes.

    PubMed

    Maity, Amit Ranjan; Palmal, Sharbari; Basiruddin, S K; Karan, Niladri Sekhar; Sarkar, Suresh; Pradhan, Narayan; Jana, Nikhil R

    2013-06-21

    Doped semiconductor nanocrystals such as Mn doped ZnS, Mn doped ZnSe and Cu doped InZnS, are considered as new classes of fluorescent biological probes with low toxicity. Although the synthesis in high quality of such nanomaterials is now well established, transforming them into functional fluorescent probes remains a challenge. Here we report a fluorescent cellular imaging probe made of high quality doped semiconductor nanocrystals. We have identified two different coating approaches suitable for transforming the as synthesized hydrophobic doped semiconductor nanocrystals into water-soluble functional nanoparticles. Following these approaches we have synthesized TAT-peptide- and folate-functionalized nanoparticles of 10-80 nm hydrodynamic diameter and used them as a fluorescent cell label. The results shows that doped semiconductor nanocrystals can be an attractive alternative for conventional cadmium based quantum dots with low toxicity.

  6. Dynamics of carrier recombination in a semiconductor laser structure

    SciTech Connect

    Dzhioev, R. I. Kavokin, K. V.; Kusrayev, Yu. G.; Poletaev, N. K.

    2015-11-15

    Carrier-recombination dynamics is studied by the method of optical orientation at room temperature in the active layer of a laser diode structure. The dependence of the degree of electron-spin orientation on the excitation density is attributed to saturation of the nonradiative-recombination channel. The time of electron capture at recombination centers is determined to be τ{sub e} = 5 × 10{sup –9} s. The temperature of nonequilibrium electrons heated by a He–Ne laser is estimated.

  7. Direct laser fabrication of nanowires on semiconductor surfaces

    NASA Astrophysics Data System (ADS)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    Periodic nanowires are observed from (001) orientation of Si and GaAs when the surfaces are irradiated interferentially by high power laser pulses. These nanowires are self-assembled and can be strain-free while their period is consistent with interference period. The nanowire morphologies are studied by atomic force microscopy. The observed period between nanowires depends on the wavelengths used and interference angle. The nanowire width increases with laser intensity. The narrowest nanowires observed have the width smaller than 20 nm, which is more than 10 times smaller than the interference period.

  8. Battery-driven miniature LDA system with semiconductor laser diode

    NASA Astrophysics Data System (ADS)

    Damp, S.

    1988-06-01

    A one-component miniature system with dimensions of 11 by 4 by 4 cubic centimeters for laser-Doppler anemometry (LDA) is described. As power supply a 12V battery or any other source with the capability to drive a current up to 200mA can be used. The system contains the whole electronics to drive the used laser diode is a safe way. The electronics to amplify and buffer the LDA-signal which is received by a PIN-diode is included. The output of the system can directly fit a filterbank for example. Possible applications in rough environments are mentioned. Measurements show the reliability of the system.

  9. Investigation of GaAs photoconductive switches triggered by 900nm semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Ma, Deming; Shi, Wei; Ma, Xiangrong; Wang, Xinmei; Pei, Tao

    2008-12-01

    Experiment of a lateral semi-insulating GaAs photoconductive semiconductor switch (SI-GaAs PCSS) with different electrode gaps triggered by 900nm semiconductor laser is reported. With the biased voltage of 0.2KV~3.0KV, the linear electrical pulse is outputted by SI-GaAs PCSS. When laser energy is very low, the semi-insulating GaAs PCSS with 1.5mm electrode gap is triggered by laser pulse, the output electrical pulse samples is instable. When the energy of the laser increases, the amplitude and the width of the electrical pulse also increase. It indicates that a stable electrical pulse is obtained while laser energy is high. With the biased voltage of 2.8kV, the SI-GaAs PCSS with 3mm electrode gap is triggered by laser pulse about 10nJ in 200ns at 900nm. The SI-GaAs PCSS switches a electrical pulse with a voltage up to 80V. The absorption mechanism by Franz-Keldysh effect under high-intensity electric field and EL2 deep level defects is discussed.

  10. A Study on Photothermal Waves in a Semiconductor Material Photogenerated by a Focused Laser Beam

    NASA Astrophysics Data System (ADS)

    Abbas, Ibrahim A.; Aly, K. A.

    2016-11-01

    In this work, the theory of coupled plasma, thermal and elastic waves were used to investigate the wave propagation on semiconductor material during photo-thermo-elastic process. A thin slim strip (TSS) medium, elastic semiconductor with isotropic and homogeneous thermal and elastic properties have been considered. The plasma, thermal and elastic waves in a TSS photo generated by a focused and intensity modulated laser beam were analyzed. Laplace transform techniques and eigenvalue approach were used to obtain the analytical solutions for carrier density, displacement, temperature, and stress. Numerical computations have been carried out on silicon-like semiconductor material. The results are presented graphically to show the effect of the coupling between the plasma, thermal, and elastic waves.

  11. Doped semiconductor nanocrystal based fluorescent cellular imaging probes

    NASA Astrophysics Data System (ADS)

    Maity, Amit Ranjan; Palmal, Sharbari; Basiruddin, Sk; Karan, Niladri Sekhar; Sarkar, Suresh; Pradhan, Narayan; Jana, Nikhil R.

    2013-05-01

    Doped semiconductor nanocrystals such as Mn doped ZnS, Mn doped ZnSe and Cu doped InZnS, are considered as new classes of fluorescent biological probes with low toxicity. Although the synthesis in high quality of such nanomaterials is now well established, transforming them into functional fluorescent probes remains a challenge. Here we report a fluorescent cellular imaging probe made of high quality doped semiconductor nanocrystals. We have identified two different coating approaches suitable for transforming the as synthesized hydrophobic doped semiconductor nanocrystals into water-soluble functional nanoparticles. Following these approaches we have synthesized TAT-peptide- and folate-functionalized nanoparticles of 10-80 nm hydrodynamic diameter and used them as a fluorescent cell label. The results shows that doped semiconductor nanocrystals can be an attractive alternative for conventional cadmium based quantum dots with low toxicity.Doped semiconductor nanocrystals such as Mn doped ZnS, Mn doped ZnSe and Cu doped InZnS, are considered as new classes of fluorescent biological probes with low toxicity. Although the synthesis in high quality of such nanomaterials is now well established, transforming them into functional fluorescent probes remains a challenge. Here we report a fluorescent cellular imaging probe made of high quality doped semiconductor nanocrystals. We have identified two different coating approaches suitable for transforming the as synthesized hydrophobic doped semiconductor nanocrystals into water-soluble functional nanoparticles. Following these approaches we have synthesized TAT-peptide- and folate-functionalized nanoparticles of 10-80 nm hydrodynamic diameter and used them as a fluorescent cell label. The results shows that doped semiconductor nanocrystals can be an attractive alternative for conventional cadmium based quantum dots with low toxicity. Electronic supplementary information available: Characterization details of coating and

  12. Solid-state semiconductor optical cryocooler based on CdS nanobelts.

    PubMed

    Li, Dehui; Zhang, Jun; Wang, Xinjiang; Huang, Baoling; Xiong, Qihua

    2014-08-13

    We demonstrate the laser cooling of silicon-on-insulator (SOI) substrate using CdS nanobelts. The local temperature change of the SOI substrate exactly beneath the CdS nanobelts is deduced from the ratio of the Stokes and anti-Stokes Raman intensities from the Si layer on the top of the SOI substrate. We have achieved a 30 and 20 K net cooling starting from 290 K under a 3.8 mW 514 nm and a 4.4 mW 532 nm pumping, respectively. In contrast, a laser heating effect has been observed pumped by 502 and 488 nm lasers. Theoretical analysis based on the general static heat conduction module in the Ansys program package is conducted, which agrees well with the experimental results. Our investigations demonstrate the laser cooling capability of an external thermal load, suggesting the applications of II-VI semiconductors in all-solid-state optical cryocoolers.

  13. Synchronization and control of chaos in semiconductor laser arrays

    NASA Astrophysics Data System (ADS)

    Pethel, Shawn Dwayne

    2000-08-01

    Diode lasers are miniature, highly efficient, reliable sources of low-power coherent light. For high-power applications diode lasers can be fabricated into arrays. Although beam power can be easily increased this way, it is at the expense of beam quality. The in-phase state is inherently unstable in diode laser arrays and for many parameters these devices display spatio-temporal chaos in the near field. This dissertation uses a coupled-mode model to study the dynamics of a weakly-coupled array of diode lasers. A stability analysis is done to investigate the effect of the coupling parameter on various phase- locked states. Possible control techniques are discussed and analyzed. It is found that a knowledge of relative phase across the array along with the ability to rapidly modulate the injection current can lead to a very robust method of phase control. In addition to the power- combining in-phase mode it is shown that other phase states can be stabilized with applications to beam steering.

  14. Time delays in lead-salt semiconductor diode lasers

    NASA Astrophysics Data System (ADS)

    Qadeer, A.; Reed, J.; Bryant, F. J.

    1984-03-01

    Time delays of typically 15 17μ have been measured directly for PbS1-xSex, Pb1-xSnxSe and Pb1-xSnxTe diode lasers at injection levels just above threshold in each case. The corresponding minority carrier lifetimes, as determined using the one-carrier injection model, were typically 2 4μ.

  15. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: High-frequency impedance and spontaneous carrier lifetime in narrow-stripe semiconductor injection lasers

    NASA Astrophysics Data System (ADS)

    Hoernlein, W.

    1988-11-01

    Measurements were made of the complex reflection coefficient of hf (10-400 MHz) signals from semiconductor injection lasers supplied with a direct bias current ranging from several milliamperes up to the threshold value or higher. The hf impedance was calculated. The parameters of the equivalent electrical circuit made it possible to predict the modulation characteristics. The impedance corresponding to currents below the lasing threshold was used to find the differential carrier lifetime from the RC constant of the p-n junction of a laser diode. A description of the apparatus is supplemented by an account of the method used in calculation of the electrical parameters and carrier lifetimes. The first results obtained using this apparatus and method are reported.

  16. Optical injection of quantum dash semiconductor lasers at 1550nm for tunable photonic oscillators

    NASA Astrophysics Data System (ADS)

    Pochet, M.; Naderi, N. A.; Kovanis, V.; Lester, L. F.

    2011-02-01

    In this manuscript, we will theoretically compute and experimentally investigate the dynamics of an optically injected nanostructure laser as a function of the injection strength and the optical detuning frequency. A model describing the optically-injected semiconductor laser is derived in dimensionless format that accounts for the large nonlinear gain component associated with nanostructure semiconductor lasers through the gain coefficient's derivative with respect to perturbations in the carrier and photon density. The nonlinear gain (carrier) relaxation rate and gain compression coefficient account for the perturbation in the slave laser's photon density, and are theoretically shown to have a strong impact on the level of stability exhibited by the optically-injected laser. The theoretical model is experimentally verified through the optical-injection of a quantum-dash Fabry-Perot laser at an operating wavelength of 1550 nm. The quantum-dash laser's large damping rate and sufficiently small linewidth enhancement factor are observed to inhibit period-doubling and chaotic operation under zero frequency-detuning conditions. Additionally, the optically injected quantum-dash laser is found to exhibit a large period-one operational state as the injection strength and the detuning frequency are varied, resulting in a highly tunable microwave frequency in the coupled system's equilibrium state. The enhanced and undamped relaxation oscillations of the period-one state are discussed as a building block for tunable photonic oscillators in various RF photonics applications. Finally a path towards realizing an optically-injected diode laser with a THz resonance frequency will be reviewed.

  17. Low-noise Raman fiber amplifier pumped by semiconductor disk laser.

    PubMed

    Chamorovskiy, A; Rautiainen, J; Rantamäki, A; Okhotnikov, O G

    2011-03-28

    A 1.3 µm Raman fiber amplifier pumped by 1.22 µm semiconductor disk laser in co-propagation geometry is demonstrated. Measured relative intensity noise of -148 dB/Hz over frequency range up to 3.5 GHz was measured at 900 mW of pump power. 9 dB gain was achieved with co-propagating pumping geometry with less than 2 dB additional noise induced by amplifier to the signal. Nearly shot-noise-limited operation of semiconductor disk laser combined with the diffraction-limited beam allows for efficient core-pumping of the single-mode fiber Raman amplifiers and represents a highly practical approach which takes full advantage of co-propagating pumping.

  18. New Role for Nonlinear Dynamics and Chaos in Integrated Semiconductor Laser Technology

    NASA Astrophysics Data System (ADS)

    Yousefi, M.; Barbarin, Y.; Beri, S.; Bente, E. A. J. M.; Smit, M. K.; Nötzel, R.; Lenstra, D.

    2007-01-01

    Using an integrated colliding-pulse mode-locked semiconductor laser, we demonstrate the existence of nonlinear dynamics and chaos in photonic integrated circuits (PICs) by demonstrating a period-doubling transition into chaos. Unlike their stand-alone counterparts, the dynamics of PICs are more stable over the lifetime of the system, reproducible from batch to batch and on faster time scales due to the small sizes of PICs.

  19. Spiking Excitable Semiconductor Laser as Optical Neurons: Dynamics, Clustering and Global Emerging Behaviors

    DTIC Science & Technology

    2014-06-28

    feedback. Presented by C. Masoller 12. Congreso de Fisica Estadistica (FISES), Ourense, Spain, April, 2014. Characterizing the complex dynamics of a...rogue waves in semiconductor lasers. To be presented by J. Zamora Munt 5.3. Poster presentations 1. Congreso de Fisica Estadistica (FISES), Palma de...injection. Presented by M. S. Torre 5. Congreso de Fisica Estadistica (FISES), Ourense, Spain, April, 2014. Unveiling the complex organization of

  20. Clamping of the Linewidth Enhancement Factor in Narrow Quantum-Well GRINSCH Semiconductor Lasers

    SciTech Connect

    Bossert, D.; Chow, W.W.; Hader, J.; Koch, S.W.; Moloney, J.V.; Stohls, J.

    1999-01-20

    The linewidth enhancement factor in single quantum-well GRINSCH semiconductor lasers is investigated theoretically and experimentally. For thin wells a small linewidth enhancement factor is obtained which clamps with increasing carrier density, in contrast to the monotonous increase observed for thicker wells. Microscopic many-body calculations reproduce the experimental observations attributing the clamping to a subtle interplay between excitation dependent gain shifts and carrier population distributions.

  1. Lateral modes of broad area semiconductor lasers - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.; Larsson, Anders G.; Cody, Jeffrey G.

    1991-01-01

    Calculations of the lateral modes of an ideal broad area laser, including the nonlinear interaction between the carriers and the optical field, are made. The results include periodically modulated near fields and single- and double-lobed far fields similar to those previously measured. The unsaturable losses are higher and quantum efficiencies are lower than those determined from plane-wave approximations. Broad area InGaAs-GaAlAs-GaAs quantum-well lasers were fabricated and measured and found to closely agree with the theory in near, far, and spectrally resolved near fields. An occultation experiment on the far field confirms previously predicted unstable resonatorlike modes with V-shaped fronts.

  2. Extreme intensity pulses in a semiconductor laser with a short external cavity.

    PubMed

    Reinoso, Jose A; Zamora-Munt, Jordi; Masoller, Cristina

    2013-06-01

    We present a numerical study of the pulses displayed by a semiconductor laser with optical feedback in the short-cavity regime, such that the external cavity round-trip time is shorter than the laser relaxation oscillation period. For certain parameters there are occasional pulses, which are high enough to be considered extreme events. We characterize the bifurcation scenario that gives rise to such extreme pulses and study the influence of noise. We demonstrate intermittency when the extreme pulses appear and hysteresis when the attractor that sustains these pulses is destroyed. We also show that this scenario is robust under the inclusion of noise.

  3. Tunable directly modulated fiber ring laser using a reflective semiconductor optical amplifier for WDM access networks.

    PubMed

    Lin, Zih-Rong; Liu, Cheng-Kuang; Jhang, Yu-Jhu; Keiser, Gerd

    2010-08-16

    We have proposed a stable, wideband, and tunable directly modulated fiber ring laser (TDMFRL) by using a reflective semiconductor optical amplifier (RSOA) and an optical tunable filter (OTF). For use in a bidirectional access network, the TDMFRL not only generates downstream data traffic but also serves as the wavelength-selecting injection light source for the Fabry-Pérot laser diode (FP-LD) located at the subscriber site. We experimentally demonstrated a bidirectional transmission at 1.25-Gb/s direct modulation over a 25-km single-mode fiber (SMF), thereby showing good performance in a wavelength division multiplexing (WDM) access network.

  4. Ag-based semiconductor photocatalysts in environmental purification

    NASA Astrophysics Data System (ADS)

    Li, Jiade; Fang, Wen; Yu, Changlin; Zhou, Wanqin; zhu, Lihua; Xie, Yu

    2015-12-01

    Over the past decades, with the fast development of global industrial development, various organic pollutants discharged in water have become a major source of environmental pollution in waste fields. Photocatalysis, as green and environmentally friendly technology, has attracted much attention in pollutants degradation due to its efficient degradation rate. However, the practical application of traditional semiconductor photocatalysts, e.g. TiO2, ZnO, is limited by their weak visible light adsorption due to their wide band gaps. Nowadays, the study in photocatalysts focuses on new and narrow band gap semiconductors. Among them, Ag-based semiconductors as promising visible light-driven photocatalysts have aroused much interesting due to their strong visible light responsibility. Most of Ag-based semiconductors could exhibit high initial photocatalytic activity. But they easy suffer from poor stability because of photochemical corrosion. Design heterojunction, increasing specific surface area, enriching pore structure, regulating morphology, controlling crystal facets, and producing plasmonic effects were considered as the effective strategies to improve the photocatalytic performance of Ag-based photocatalyts. Moreover, combining the superior properties of carbon materials (e.g. carbon quantum dots, carbon nano-tube, carbon nanofibers, graphene) with Ag-based semiconductor could produce high efficient composite photocatalyts.

  5. Near infrared laser stimulation of human neural stem cells into neurons on graphene nanomesh semiconductors.

    PubMed

    Akhavan, Omid; Ghaderi, Elham; Shirazian, Soheil A

    2015-02-01

    Reduced graphene oxide nanomeshes (rGONMs), as p-type semiconductors with band-gap energy of ∼ 1 eV, were developed and applied in near infrared (NIR) laser stimulation of human neural stem cells (hNSCs) into neurons. The biocompatibility of the rGONMs in growth of hNSCs was found similar to that of the graphene oxide (GO) sheets. Proliferation of the hNSCs on the GONMs was assigned to the excess oxygen functional groups formed on edge defects of the GONMs, resulting in superhydrophilicity of the surface. Under NIR laser stimulation, the graphene layers (especially the rGONMs) exhibited significant cell differentiations, including more elongations of the cells and higher differentiation of neurons than glia. The higher hNSC differentiation on the rGONM than the reduced GO (rGO) was assigned to the stimulation effects of the low-energy photoexcited electrons injected from the rGONM semiconductors into the cells, while the high-energy photoelectrons of the rGO (as a zero band-gap semiconductor) could suppress the cell proliferation and/or even cause cell damages. Using conventional heating of the culture media up to ∼ 43 °C (the temperature typically reached under the laser irradiation), no significant differentiation was observed in dark. This further confirmed the role of photoelectrons in the hNSC differentiation.

  6. Tailored surface-enhanced Raman nanopillar arrays fabricated by laser-assisted replication for biomolecular detection using organic semiconductor lasers.

    PubMed

    Liu, Xin; Lebedkin, Sergei; Besser, Heino; Pfleging, Wilhelm; Prinz, Stephan; Wissmann, Markus; Schwab, Patrick M; Nazarenko, Irina; Guttmann, Markus; Kappes, Manfred M; Lemmer, Uli

    2015-01-27

    Organic semiconductor distributed feedback (DFB) lasers are of interest as external or chip-integrated excitation sources in the visible spectral range for miniaturized Raman-on-chip biomolecular detection systems. However, the inherently limited excitation power of such lasers as well as oftentimes low analyte concentrations requires efficient Raman detection schemes. We present an approach using surface-enhanced Raman scattering (SERS) substrates, which has the potential to significantly improve the sensitivity of on-chip Raman detection systems. Instead of lithographically fabricated Au/Ag-coated periodic nanostructures on Si/SiO2 wafers, which can provide large SERS enhancements but are expensive and time-consuming to fabricate, we use low-cost and large-area SERS substrates made via laser-assisted nanoreplication. These substrates comprise gold-coated cyclic olefin copolymer (COC) nanopillar arrays, which show an estimated SERS enhancement factor of up to ∼ 10(7). The effect of the nanopillar diameter (60-260 nm) and interpillar spacing (10-190 nm) on the local electromagnetic field enhancement is studied by finite-difference-time-domain (FDTD) modeling. The favorable SERS detection capability of this setup is verified by using rhodamine 6G and adenosine as analytes and an organic semiconductor DFB laser with an emission wavelength of 631.4 nm as the external fiber-coupled excitation source.

  7. High-power high-brightness semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Botez, D.

    2005-01-01

    Broad-stripe (greater than or equal to 100 microns) diode lasers have achieved CW powers as high as 15W, and wallplug efficiencies as high as 70%. For high coherent power photonic-crystal structures with modulated gain, that is active photonic crystals (APCs), of large index steps have been used, as early as 1988, for effective lateral-mode control range in large-aperture (100-200 microns) devices. Photonic-bandpass (PBP) structures relying on long-range resonant leaky-wave coupling, so called ROW arrays, have allowed stable, near-diffraction-limited beam operation to powers as high as 1.6W CW and 10W peak pulsed. Photonic-bandgap (PBG) structures with a built-in lattice defect, so called ARROW lasers, have provided up to 0.5W CW stable, single-mode power and hold the potential for 1W CW highly reliable single-mode operation. The solution for high-efficiency surface emission, from 2nd-order DFB/DBR lasers, in a single-lobe beam pattern was found in 2000. Single-lobe and single-mode operation in a diffraction-limited beam orthonormal to the chip surface was demonstrated, which opens the way for the realization of 2-D surface-emitting, 2nd-order APCs for the stable generation of watts of CW single-lobe, single-mode power from large 2-D apertures, as well as scalability of such devices at the wafer level.

  8. Semiconductor Laser Diodes and the Design of a D.C. Powered Laser Diode Drive Unit

    DTIC Science & Technology

    1988-06-01

    the design of a laser diode modulation circuit is the determination of the input imped- ence and equivalent circuit of the laser diode and packag- ing...current source with a high internal impedance as compared to the input imped- ance of the laser. [Ref. l:p. 33] Summarizing the above, laser diodes...switches. The modula- tion circuitry is connected in parallel with the laser diode and provides a modulated input to the laser diode superim- posed onto

  9. All-optical noninvasive chaos control of a semiconductor laser.

    PubMed

    Schikora, S; Wünsche, H-J; Henneberger, F

    2008-08-01

    We demonstrate experimentally control of a chaotic system on time scales much shorter than in any previous study. Combining a multisection laser with an external Fabry-Perot etalon, the chaotic output transforms into a regular intensity self-pulsation with a frequency in the 10-GHz range. The control is noninvasive as the feedback from the etalon is minimum when the target state is reached. The optical phase is identified as a crucial control parameter. Numerical simulations agree well with the experimental data and uncover global control properties.

  10. Subpicometer Length Measurement Using Semiconductor Laser Tracking Frequency Gauge

    NASA Technical Reports Server (NTRS)

    Thapa, Rajesh; Phillips, James D.; Rocco, Emanuele; Reasenburg, Robert D.

    2011-01-01

    We have demonstrated heretofore unattained distance precision of 0:14pm (2pm) incremental and 14nm (2.9 micrometers) absolute in a resonant (nonresonant) interferometer at an averaging time of 1 s, using inexpensive telecommunications diode lasers. We have controlled the main source of error, that due to spurious reflection and the resulting amplitude modulation. In the resonant interferometer, absolute distance precision is well under lambda/6. Therefore, after an interruption, an absolute distance measurement can be used to return to the same interferometer order.

  11. Raman Studies of Surface Temperature in Laser-Heated Semiconductors.

    DTIC Science & Technology

    1985-02-07

    and A. Compaan, Appi. Phys. Lett. 38, 3 (1981). 3. M. C. Lee, It. W. Lo, A. Aydinli , and A. Compaan, Appl. Phys. Lett. 38, 7 (1981). 4. A. Compaan, H...W. Lo, A. Aydinli , and M. C. Lee, Laser and Electron- Beam Solid Interactions and Materials Procesin ed. by Gibbons. Hess and Sigmon (Elsevier North...Holland, Amsterdam, 1981), p. 15. ~.A. Aydinli , H. W. La, M. C. Lee, and A. Comnpaan, Phys. Rev. Lett. 4 46, 25 (1981). 6. A. Aydinli , A. Compaan, H

  12. Two semiconductor ring lasers coupled by a single-waveguide for optical memory operation

    NASA Astrophysics Data System (ADS)

    Van der Sande, Guy; Coomans, Werner; Gelens, Lendert

    2014-05-01

    Semiconductor ring lasers are semiconductor lasers where the laser cavity consists of a ring-shaped waveguide. SRLs are highly integrable and scalable, making them ideal candidates for key components in photonic integrated circuits. SRLs can generate light in two counterpropagating directions between which bistability has been demonstrated. Hence, information can be coded into the emission direction. This bistable operation allows SRLs to be used in systems for all-optical switching and as all-optical memories. For the demonstration of fast optical flip-flop operation, Hill et al. [Nature 432, 206 (2004)] fabricated two SRLs coupled by a single waveguide, rather than a solitary SRL. Nevertheless, the literature shows that a single SRL can also function perfectly as an all-optical memory. In our recent paper [W. Coomans et al., Phys. Rev. A 88, 033813, (2013)], we have raised the question whether coupling two SRLs to realize a single optical memory has any advantage over using a solitary SRL, taking into account the obvious disadvantage of a doubled footprint and power consumption. To provide the answer, we have presented in that paper a numerical study of the dynamical behavior of semiconductor ring lasers coupled by a single bus waveguide, both when weakly coupled and when strongly coupled. We have provided a detailed analysis of the multistable landscape in the coupled system, analyzed the stability of all solutions and related the internal dynamics in the individual lasers to the field effectively measured at the output of the waveguide. We have shown which coupling phases generally promote instabilities and therefore need to be avoided in the design. Regarding all-optical memory operation, we have demonstrated that there is no real advantage for bistable memory operation compared to using a solitary SRL. An increased power suppression ratio has been found to be mainly due to the destructive interference of the SRL fields at the low power port. Also

  13. Modeling pulsed-laser melting of embedded semiconductor nanoparticles

    SciTech Connect

    Sawyer, C.A.; Guzman, J.; Boswell-Koller, C.N.; Sherburne, M.P.; Mastandrea, J.P.; Bustillo, K.C.; Ager III, J.W.; Haller, E.E.; Chrzan, D.C.

    2011-05-18

    Pulsed-laser melting (PLM) is commonly used to achieve a fast quench rate in both thin films and nanoparticles. A model for the size evolution during PLM of nanoparticles confined in a transparent matrix, such as those created by ion-beam synthesis, is presented. A self-consistent mean-field rate equations approach that has been used successfully to model ion beam synthesis of germanium nanoparticles in silica is extended to include the PLM process. The PLM model includes classical optical absorption, multiscale heat transport by both analytical and finite difference methods, and melting kinetics for confined nanoparticles. The treatment of nucleation and coarsening behavior developed for the ion beam synthesis model is modified to allow for a non-uniform temperature gradient and for interacting liquid and solid particles with different properties. The model allows prediction of the particle size distribution after PLM under various laser fluences, starting from any particle size distribution including as-implanted or annealed simulated samples. A route for narrowing the size distribution of embedded nanoparticles is suggested, with simulated distribution widths as low as 15% of the average size.

  14. Modeling pulsed-laser melting of embedded semiconductor nanoparticles

    NASA Astrophysics Data System (ADS)

    Sawyer, C. A.; Guzman, J.; Boswell-Koller, C. N.; Sherburne, M. P.; Mastandrea, J. P.; Bustillo, K. C.; Ager, J. W.; Haller, E. E.; Chrzan, D. C.

    2011-11-01

    Pulsed-laser melting (PLM) is commonly used to achieve a fast quench rate in both thin films and nanoparticles. A model for the size evolution during PLM of nanoparticles confined in a transparent matrix, such as those created by ion-beam synthesis, is presented. A self-consistent mean-field rate equations approach that has been used successfully to model ion beam synthesis of germanium nanoparticles in silica is extended to include the PLM process. The PLM model includes classical optical absorption, multiscale heat transport by both analytical and finite difference methods, and melting kinetics for confined nanoparticles. The treatment of nucleation and coarsening behavior developed for the ion beam synthesis model is modified to allow for a nonuniform temperature gradient and for interacting liquid and solid particles with different properties. The model allows prediction of the particle size distribution after PLM under various laser fluences, starting from any particle size distribution including as-implanted or annealed simulated samples. A route for narrowing the size distribution of embedded nanoparticles is suggested, with simulated distribution widths as low as 15% of the average size.

  15. Future of Semiconductor Based Thermal Neutron Detectors

    SciTech Connect

    Nikolic, R J; Cheung, C L; Reinhardt, C E; Wang, T F

    2006-02-22

    Thermal neutron detectors have seen only incremental improvements over the last decades. In this paper we overview the current technology of choice for thermal neutron detection--{sup 3}He tubes, which suffer from, moderate to poor fieldability, and low absolute efficiency. The need for improved neutron detection is evident due to this technology gap and the fact that neutrons are a highly specific indicator of fissile material. Recognizing this need, we propose to exploit recent advances in microfabrication technology for building the next generation of semiconductor thermal neutron detectors for national security requirements, for applications requiring excellent fieldability of small devices. We have developed an innovative pathway taking advantage of advanced processing and fabrication technology to produce the proposed device. The crucial advantage of our Pillar Detector is that it can simultaneously meet the requirements of high efficiency and fieldability in the optimized configuration, the detector efficiency could be higher than 70%.

  16. Multiphysics modeling of non-linear laser-matter interactions for optically active semiconductors

    NASA Astrophysics Data System (ADS)

    Kraczek, Brent; Kanp, Jaroslaw

    Development of photonic devices for sensors and communications devices has been significantly enhanced by computational modeling. We present a new computational method for modelling laser propagation in optically-active semiconductors within the paraxial wave approximation (PWA). Light propagation is modeled using the Streamline-upwind/Petrov-Galerkin finite element method (FEM). Material response enters through the non-linear polarization, which serves as the right-hand side of the FEM calculation. Maxwell's equations for classical light propagation within the PWA can be written solely in terms of the electric field, producing a wave equation that is a form of the advection-diffusion-reaction equations (ADREs). This allows adaptation of the computational machinery developed for solving ADREs in fluid dynamics to light-propagation modeling. The non-linear polarization is incorporated using a flexible framework to enable the use of multiple methods for carrier-carrier interactions (e.g. relaxation-time-based or Monte Carlo) to enter through the non-linear polarization, as appropriate to the material type. We demonstrate using a simple carrier-carrier model approximating the response of GaN. Supported by ARL Materials Enterprise.

  17. Enhancement of spin coherence using Q-factor engineering in semiconductor microdisc lasers.

    PubMed

    Ghosh, S; Wang, W H; Mendoza, F M; Myers, R C; Li, X; Samarth, N; Gossard, A C; Awschalom, D D

    2006-04-01

    Semiconductor microcavities offer unique means of controlling light-matter interactions in confined geometries, resulting in a wide range of applications in optical communications and inspiring proposals for quantum information processing and computational schemes. Studies of spin dynamics in microcavities, a new and promising research field, have revealed effects such as polarization beats, stimulated spin scattering and giant Faraday rotation. Here, we study the electron spin dynamics in optically pumped GaAs microdisc lasers with quantum wells and interface-fluctuation quantum dots in the active region. In particular, we examine how the electron spin dynamics are modified by the stimulated emission in the discs, and observe an enhancement of the spin-coherence time when the optical excitation is in resonance with a high-quality (Q approximately 5,000) lasing mode. This resonant enhancement, contrary to expectations from the observed trend in the carrier-recombination time, is then manipulated by altering the cavity design and dimensions. In analogy with devices based on excitonic coherence, this ability to engineer coherent interactions between electron spins and photons may provide new pathways towards spin-dependent quantum optoelectronics.

  18. Electrical addressing and temporal tweezing of localized pulses in passively-mode-locked semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Camelin, P.; Javaloyes, J.; Marconi, M.; Giudici, M.

    2016-12-01

    We show that the pumping current is a convenient parameter for manipulating the temporal localized structures (LSs), also called localized pulses, found in passively-mode-locked vertical-cavity surface-emitting lasers. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing one to control the position and the dynamics of LSs. We show that the localized pulse drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on a finite time scale and breaks the parity invariance along the cavity, thus leading to a different paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. Starting from a generic model of passive mode locking based upon delay differential equations, we deduce the effective equations of motion for these LSs in a time-dependent current landscape.

  19. Indirect detection by semiconductor laser-induced fluorometry in micellar electrokinetic chromatography

    NASA Astrophysics Data System (ADS)

    Kaneta, Takashi; Imasaka, Totaro

    1995-05-01

    Indirect fluorescence detection of electrically neutral compounds separated by micellar electrokinetic chromatography is performed using a semiconductor laser as an exciting light source. Oxazine 750 is used as a visualizing agent of which absorption maximum is near 680 nm. A surfactant, tetradecyltrimethylammonium chloride, is used to form micelles and to prevent adsorption of oxazine 750 with a positive charge on the capillary wall negatively charged. This surfactant coats on the capillary wall so that oxazine 750 is repulsed electrically on the capillary wall. In this technique, some aromatic compounds with relatively polar functional groups, such as aniline and nitrobenzene, could be separated and detected, while nonpolar compounds such as benzene and toluene can not be detected. The range of the detection limit is from 4.2 X 10-4 to 1.6 X 10-3 M (S/N equals 3) for the aromatic compounds. The detection mechanism is based on enhancement of the fluorescence intensity in the micellar solution and on exclusion of the fluorophore attached at the hydrophilic moiety of the micelle by a hydrophilic sample.

  20. Near-field and far-field engineering of semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Yu, Nanfang

    Plasmonics focuses on the interaction between light and metallic films or nanostructures. In the last two decades, intensive research efforts were devoted to exploring the extremely broad applications of plasmonics. My research combines the versatility of plasmonics with active light sources, i.e., quantum cascade lasers (QCLs). This thesis focuses on the application of plasmonics in near-field and far-field engineering of semiconductor lasers, specifically, subwavelength focusing in the near-field, and laser beam collimation and polarization control. The first chapter of this thesis lays out fundamental materials necessary for understanding the following chapters. Systematic simulation and experimental results are presented in Chapter 2 to demonstrate that the integration of a suitably designed one dimensional or two dimensional plasmonic structures on the facet of QCLs can reduce the beam divergence by more than one order of magnitude. The devices with optimized collimators preserve a high output power, comparable to that of the unpatterned lasers. Chapter 3 demonstrates that the polarization state of the output of semiconductor lasers can be controlled by defining plasmonic structures on the laser facet. An integrated plasmonic polarizer can project the polarization of a semiconductor laser onto other directions. By patterning a facet with two orthogonal grating-aperture structures, a QCL can produce emission consisting of a superposition of a linearly and right-circularly polarized light, a first step towards a circularly-polarized laser. Chapter 4 presents experimental work on the coupled-rod antennas and the bowtie antennas patterned on the facet of QCLs. Both designs can provide an optical field confinement on the order of lambda/50 and with peak intensity on the order of 1 GW/cm2 in the antenna gap. The bowtie devices are more advanced due to better confinement of light into a single spot. Chapter 5 and 6 discuss two side research topics. Chapter 5

  1. Concealment of time delay signature of chaotic output in a slave semiconductor laser with chaos laser injection

    NASA Astrophysics Data System (ADS)

    Wu, Tianan; Sun, Weiyang; Zhang, Xiaoxu; Zhang, Shenghai

    2016-12-01

    An improved chaotic laser system, which has a slave semiconductor laser (SL) injected by a master SL with double optical feedback (DOF), is proposed, so that the time delay (TD) signature can be successfully concealed from both intensity and phase chaos via choosing appropriate parameters. The TD signature is investigated by employing autocorrelation function (ACF) and mutual information (MI) function. Through analyzing the influence on TD signature in the region of injection current and injection strength for the slave SL, we find that, for both intensity chaos and phase chaos, the TD signature can be easily concealed under weak injection strength. When the injection strength is strong, we can not only successfully conceal TD signature, but also improve the bandwidth of chaotic laser output by choosing the optimal detuning frequency.

  2. Dilute ferromagnetic semiconductors prepared by the combination of ion implantation with pulse laser melting

    NASA Astrophysics Data System (ADS)

    Zhou, Shengqiang

    2015-07-01

    Combining semiconducting and ferromagnetic properties, dilute ferromagnetic semiconductors (DFS) have been under intensive investigation for more than two decades. Mn doped III-V compound semiconductors have been regarded as the prototype of DFS from both experimental and theoretic investigations. The magnetic properties of III-V:Mn can be controlled by manipulating free carriers via electrical gating, as for controlling the electrical properties in conventional semiconductors. However, the preparation of DFS presents a big challenge due to the low solubility of Mn in semiconductors. Ion implantation followed by pulsed laser melting (II-PLM) provides an alternative to the widely used low-temperature molecular beam epitaxy (LT-MBE) approach. Both ion implantation and pulsed-laser melting occur far enough from thermodynamic equilibrium conditions. Ion implantation introduces enough dopants and the subsequent laser pulse deposit energy in the near-surface region to drive a rapid liquid-phase epitaxial growth. Here, we review the experimental study on preparation of III-V:Mn using II-PLM. We start with a brief description about the development of DFS and the physics behind II-PLM. Then we show that ferromagnetic GaMnAs and InMnAs films can be prepared by II-PLM and they show the same characteristics of LT-MBE grown samples. Going beyond LT-MBE, II-PLM is successful to bring two new members, GaMnP and InMnP, into the family of III-V:Mn DFS. Both GaMnP and InMnP films show the signature of DFS and an insulating behavior. At the end, we summarize the work done for Ge:Mn and Si:Mn using II-PLM and present suggestions for future investigations. The remarkable advantage of II-PLM approach is its versatility. In general, II-PLM can be utilized to prepare supersaturated alloys with mismatched components.

  3. The next generation of high-power semiconductor diode lasers

    NASA Astrophysics Data System (ADS)

    Botez, Dan; Yang, Jane J.

    Progress made in both high-power coherent arrays for space communications and high-power incoherent arrays for efficient pumping of solid-state (Nd-YAG) laser is reviewed. It is concluded that parallel coupling in a strong index-guided structure makes it possible to increase the performance of resonant-optical-waveguide (ROW) arrays by orders of magnitude higher than that of other array types. Preliminary results from ROW arrays show greater than 2,000 h operation at 0.5-W output with little increase in drive current. Edge-emitting POW arrays are likely to reach 2-3 W continuous-wave diffraction limited power. Monolithic solid-state pumps are likely to deliver optical flux densities in excess of 1 kW/sq cm.

  4. TO packaged 650nm red semiconductor laser with transparent window

    NASA Astrophysics Data System (ADS)

    Xia, Wei; Zhu, Zhen; Li, Peixu; Su, Jian; Zhang, Xin; Xu, Xiangang

    2016-11-01

    Highly uniform solid-phase Zn-diffusion technique was developed to fabricate transparent windows for 650 nm red laser diodes (LDs). The maximum output power was up to 120 mW, which is three times higher than that for LDs without window structure. The LDs showed excellent thermal characteristics and aging reliability with TO-can package. The characteristic temperature was estimated to be 85 K in the temperature range of 25 65 °C. The LDs showed stable operation of 10 mW at a high temperature of 75 °C. After aging test of 2000 h, the elevated operation current was less than 3%, compared to the initial value. The predicted life time was over 10000 h for 10 mW operation at 75 °C.

  5. Spontaneous locking of optical vortices in coupled semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Yadin, Yoav; Scheuer, Jacob; Gross, Yoav; Orenstein, Meir

    2014-09-01

    Non-conventional emission of light, comprising engaged rotating light cogs, is measured and analyzed. The source of this unique emission is an array of coupled surface emitting lasers, each emitting an optical vortex. The complex rotating light structures are formed spontaneously by specific combinations of the individual vortices, each carrying two types of "charge": orbital angular momentum (±1 topological charge) and a relative engagement phase (0 or π). These charges determine the specific form in which the individual rotating fields are engaged to generate the emanated light gear. The experimentally observed formations and dynamic evolution of the light gears stem from the complex nonlinear dynamics of the coupled rotating-field emitters, a mechanism which we have successfully modeled and utilized for interpreting the obtained results. The engaged light gears can be used in controlled generation and transmission of multiple degrees of freedom photons, for high-bit-rate classic and quantum telecommunications, particle manipulation, and super-resolution imaging.

  6. Laser drilling of via micro-holes in single-crystal semiconductor substrates using a 1070nm fibre laser with millisecond pulse widths

    NASA Astrophysics Data System (ADS)

    Maclean, Jessica O.; Hodson, Jonathan R.; Voisey, K. T.

    2015-07-01

    Micro-machining of semiconductors is relevant to fabrication challenges within the semiconductor industry. For via holes for solar cells, laser drilling potentially avoids deep plasma etching which requires sophisticated equipment and corrosive, high purity gases. Other applications include backside loading of cold atoms into atom chips and ion traps for quantum physics research, for which holes through the semiconductor substrate are needed. Laser drilling, exploiting the melt ejection material removal mechanism, is used industrially for drilling hard to machine materials such as superalloys. Lasers of the kind used in this work typically form holes with diameters of 100's of microns and depths of a few millimetres in metals. Laser drilling of semiconductors typically uses short pulses of UV or long wavelength IR to achieve holes as small as 50 microns. A combination of material processes occurs including laser absorption, heating, melting, vaporization with vapour and dust particle ejection and resolidification. An investigation using materials with different fundamental material parameters allows the suitability of any given laser for the processing of semiconductors to be determined. We report results on the characterization of via holes drilled using a 2000 W maximum power 1070 nm fibre laser with 1-20 ms pulses using single crystal silicon, gallium arsenide and sapphire. Holes were characterised in cross-section and plan view. Significantly, relatively long pulses were effective even for wide bandgap substrates which are nominally transparent at 1070 nm. Examination of drilled samples revealed holes had been successfully generated in all materials via melt ejection.

  7. Long-wavelength fluorescent probes--chemistry and semiconductor lasers: a difficult marriage

    NASA Astrophysics Data System (ADS)

    Casay, G. A.; Czuppon, Tibor; Patonay, Gabor

    1994-07-01

    The utility of having commercially available semiconductor laser diodes (wavelengths above 680 nm) that match the absorption maximum of near-infrared dyes will be discussed. The large gaps that exist between available wavelengths has limited the use of many new NIR dyes in many fields especially in optical fiber applications. Several 2,3-naphthalocyanine dyes have been synthesized with different moieties which produce a bathochromic shift of the absorbance maximum as compared to the unsubstituted dye. The utility of NIR dyes with absorbance maximum close to the output wavelength of commercially available laser diodes is illustrated by using an optical fiber instrument developed for the detection of metal ions. Detection of contaminants in the picomolar range will be discussed. Excitation of the dye/analyte complex induced with a semiconductor laser diode and emission intensity signal collected at 820 nm will be discussed. The use of Acoustic Optical Tunable Filter (AOTF) filters to fill existing gaps in commercially available laser wavelength and the tuning of light sources using an AOTF will also be discussed. The development of these systems will allow the manufacturing of portable optical fiber detectors for applications in industry, medicine and the environment.

  8. Multi-wavelength mid-infrared micro-spectral imaging using semiconductor lasers.

    PubMed

    Guo, B; Wang, Y; Peng, C; Luo, G P; Le, H Q

    2003-07-01

    Infrared (IR, 3-12-microm) microscopic spectral imaging is an important analytical technique. Many current instruments employ thermal IR light sources, which suffer the problem of low brightness and high noise. This paper evaluates the system engineering merit in using semiconductor lasers, which offer orders-of-magnitude-higher power, brightness, and lower noise. A microscopic spectral imaging system using semiconductor lasers (quantum cascade) as illuminators, and focal plane array detectors demonstrated a high signal-to-noise ratio (> 20 dB) at video frame rate for a large illuminated area. The comparative advantages of laser vs. thermal light source are analyzed and demonstrated. Microscopic spectral imaging with fixed-wavelength and tunable lasers of 4.6-, 5.1-, 6-, and 9.3-microm wavelength was applied to a number of representative samples that consist of biological tissues (plant and animal), solid material (a stack of laminated polymers), and liquid chemical (benzene). Transmission spectral images with approximately 30-dB dynamic range were obtained with clear evidence of spectral features for different samples. The potential of more advanced systems with a wide coverage of spectral bands is discussed.

  9. Broadly tunable and multi-spectral mid-IR semiconductor lasers and applications

    NASA Astrophysics Data System (ADS)

    Peng, Chuan; Wang, Yi; Wang, Yang; Zhang, Huanlin; Luo, Guipeng; Guo, Bujin; Le, Han Q.

    2006-02-01

    This paper describes an application-centric development of broadly tunable and multi-spectral mid/long-wave IR semi-conductor lasers. Examples of various external-cavity lasers capable of broad, continuous wavelength tuning with type-I and type-II quantum cascade lasers are discussed. Laser configurations studied include conventional Littman-Metcalf, Littrow, multi-segment and Bragg-grating-coupled surface-emitting. All were capable of single-mode continuous tuning with high side-mode-suppression ratio. The lasers were evaluated with spectroscopic applications, which include wave-length-modulation spectroscopic imaging and multi-wavelength decomposition of a gas mixture. The results showed that these lasers were capable of maintaining wavelength accuracy and stability over the entire tuning range. Multi-spectral imaging with discrete wavelengths over a wide spectral range was also studied. The results with a modest 4-wavelength system demonstrated the potential application for target discrimination, detection, and identification. These results suggest potential value for broadly tunable, wide-band M/LWIR laser technology.

  10. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    SciTech Connect

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.

    1994-01-01

    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  11. Anisotropy-based crystalline oxide-on-semiconductor material

    DOEpatents

    McKee, Rodney Allen; Walker, Frederick Joseph

    2000-01-01

    A semiconductor structure and device for use in a semiconductor application utilizes a substrate of semiconductor-based material, such as silicon, and a thin film of a crystalline oxide whose unit cells are capable of exhibiting anisotropic behavior overlying the substrate surface. Within the structure, the unit cells of the crystalline oxide are exposed to an in-plane stain which influences the geometric shape of the unit cells and thereby arranges a directional-dependent quality of the unit cells in a predisposed orientation relative to the substrate. This predisposition of the directional-dependent quality of the unit cells enables the device to take beneficial advantage of characteristics of the structure during operation. For example, in the instance in which the crystalline oxide of the structure is a perovskite, a spinel or an oxide of similarly-related cubic structure, the structure can, within an appropriate semiconductor device, exhibit ferroelectric, piezoelectric, pyroelectric, electro-optic, ferromagnetic, antiferromagnetic, magneto-optic or large dielectric properties that synergistically couple to the underlying semiconductor substrate.

  12. Holmium Doped Solid State Laser Resonantly Pumped and Q-Switched by Novel GaSb-Based Photonic Devices

    DTIC Science & Technology

    2011-08-31

    demonstrated for all devices. High power 1.95µm type-I quantum-well GaSb-based diode lasers were used to pump fluoride glass holmium doped fiber...II-VI semiconductors, novel type-II quantum well Sb-based semiconductors, and holmium doped crystals, glasses and fibers can be achieved. The...resonant pumping of the holmium doped fiber laser was demonstrated in this work. (a).1. High power ~2.2 µm lasers with broadened waveguide design

  13. Linewidth enhancement factor dependence of the instability in semiconductor lasers with delayed feedback and its influence on the analyses

    NASA Astrophysics Data System (ADS)

    Wada, Kenji; Umeda, Tokuo; Cho, Yoshio

    1994-06-01

    The instability enhancement due to the linewidth enhancement factor (α-parameter) in semiconductor lasers with delayed feedback on the regime IV are explained in terms of the laser emission suppression caused by the feedback field using the phasor representation. The discrepancy of the unstable condition due to the adiabatic-following approximation (AFA) is also examined.

  14. Numerical study of wavelength-swept semiconductor ring lasers: the role of refractive-index nonlinearities in semiconductor optical amplifiers and implications for biomedical imaging applications.

    PubMed

    Bilenca, A; Yun, S H; Tearney, G J; Bouma, B E

    2006-03-15

    Recent results have demonstrated unprecedented wavelength-tuning speed and repetition rate performance of semiconductor ring lasers incorporating scanning filters. However, several unique operational characteristics of these lasers have not been adequately explained, and the lack of an accurate model has hindered optimization. We numerically investigated the characteristics of these sources, using a semiconductor optical amplifier (SOA) traveling-wave Langevin model, and found good agreement with experimental measurements. In particular, we explored the role of the SOA refractive-index nonlinearities in determining the intracavity frequency-shift-broadening and the emitted power dependence on scan speed and direction. Our model predicts both continuous-wave and pulse operation and shows a universal relationship between the output power of lasers that have different cavity lengths and the filter peak frequency shift per round trip, therefore revealing the advantage of short cavities for high-speed biomedical imaging.

  15. Optically detected carrier transport in III/V semiconductor QW structures: experiments, model calculations and applications in fast 1.55 µm laser devices

    NASA Astrophysics Data System (ADS)

    Hillmer, H.; Marcinkevičius, S.

    1998-01-01

    This paper reviews optically detected carrier dynamics in III/V semiconductor quantum well (QW) heterostructures perpendicular to the interfaces. Photoluminescence emissions originating from different semiconductor layers are recorded in a time-resolved way to monitor the carrier dynamics between these layers. The experimental methods presented provide a very high spatial and temporal resolution, partly even in the nanometer and sub-picosecond ranges, respectively. Model calculations based on a self-consistent solution of the continuity equation, the Poisson equation and rate-equation(s) are used to evaluate the experimental data. It will be demonstrated that experiments using several specially tailored semiconductor heterostructures enable the following individual dynamic effects to be studied and separated: transport in extended unquantized layers, capture into the QWs, relaxation in the QWs, tunneling between the QWs and thermal re-emission from the QWs. It will be shown that several basic physical effects have to be studied and understood before modern high-speed semiconductor laser devices can be designed and implemented. By adding levels of increasing complexity, this review starts from simple basic structures to finally approach real laser structures in a sequence of consecutive steps. AlGaInAs and GaInAsP heterostructures are compared with respect to interwell transfer efficiencies and problems in technological implementation. This review proceeds from basic research on carrier dynamics to applications in high-speed laser devices. Throughout the review an overview of the experimental and theoretical literature is given.

  16. Use of a laser for the spectral analysis of semiconductor materials

    NASA Technical Reports Server (NTRS)

    Karyakin, A. V.; Akhmanova, M. V.; Kaygorodov, V. A.

    1978-01-01

    Conventional applications of lasers for emission spectroscopy involving direct recording of light pulses of an evaporated substance emitted from the sample under the action of the laser light (direct method) were examined. Use of the laser light for conversion of the substance to a vapor and feeding the vapors into the conventional source of emission such as arc, sparks, etc. (the so called 2 stage excitation) were studied for use in the spectral analysis, of semiconductors. The direct method has a high reproducibility (5-7%); the 2 stage excitation method, characterized by the same intensity as obtained with the conventional constant, current arc, has better reproducibility than the direct method (15-20%). Both methods can be used for the analysis of samples without prior preparation. Advantages of these methods are the elimination of impurities picked up during trituration of the samples into powders and shortening of the analytical procedures.

  17. Soliton Generation in a Semiconductor Circular Ring Laser with a Y-Junction Coupler

    NASA Astrophysics Data System (ADS)

    Shih, Ming Chang; Wang, Shih Chang; Ho, Chang En; Su, Wei Chun; Chen, Sheng Tsung; Shei, Ho Ming; Tien, Chih Wei; Wu, Sheng Min

    2009-04-01

    We report the observation of the emission of solitons from a semiconductor circular ridge waveguide ring laser with a Y-junction coupler. The light-current (L-I) characteristics of the soliton emission through the nonwaveguide region, which refers to the photovoltaic solitons, has a low threshold value and a high quantum efficiency compare to the emission from the Y-junction coupler, and the spectrum of the soliton emission is similar to that of a linear strip laser with multimode emission. The feedback light from the end facet of the Y-junction coupling section continuously enhances the excitation of the photovoltaic solitons through the nonwaveguide region until the lasing condition is reached. It is suggested that the circular ring laser can be an alternative channel to light wave control in integrated optoelectronic system.

  18. Characterization of coherence-or-power selectable operation of an external-cavity semiconductor diode laser.

    PubMed

    Hyodo, Masaharu; Watanabe, Masayoshi; Kawakami, Akira; Saito, Shingo; Adachi, Masaaki

    2016-12-20

    The properties of the coherence-or-power selectable operation of an external-cavity semiconductor diode laser through the control of intracavity polarization states have been characterized in detail. In our technique, a diffraction grating and a reflector functioned as a polarization-dependent output coupler, such that the portion of light fed back to the gain medium was readily controlled by rotating the intracavity polarization axis, which resulted in the selectable operation of either a high degree of coherence or a high power for the laser output. We could continuously sweep the correlation widths over a range of approximately one order of magnitude, as well as four-fold output powers by simply rotating the intracavity half-wave plate. We also demonstrated experiments on optical phase locking, using two independent coherence-or-power selectable lasers.

  19. Monolithic dual-mode distributed feedback semiconductor laser for tunable continuous-wave terahertz generation.

    PubMed

    Kim, Namje; Shin, Jaeheon; Sim, Eundeok; Lee, Chul Wook; Yee, Dae-Su; Jeon, Min Yong; Jang, Yudong; Park, Kyung Hyun

    2009-08-03

    We report on a monolithic dual-mode semiconductor laser operating in the 1550-nm range as a compact optical beat source for tunable continuous-wave (CW) terahertz (THz) generation. It consists of two distributed feedback (DFB) laser sections and one phase section between them. Each wavelength of the two modes can be independently tuned by adjusting currents in micro-heaters which are fabricated on the top of the each DFB section. The continuous tuning of the CW THz emission from Fe(+)-implanted InGaAs photomixers is successfully demonstrated using our dual-mode laser as the excitation source. The CW THz frequency is continuously tuned from 0.17 to 0.49 THz.

  20. High-order diffraction gratings for high-power semiconductor lasers

    SciTech Connect

    Vasil'eva, V. V.; Vinokurov, D. A.; Zolotarev, V. V.; Leshko, A. Yu.; Petrunov, A. N.; Pikhtin, N. A.; Rastegaeva, M. G.; Sokolova, Z. N. Shashkin, I. S.; Tarasov, I. S.

    2012-02-15

    A deep diffraction grating with a large period ({approx}2 {mu}m) within one of the cladding layers is proposed for the implementation of selective feedback in a semiconductor laser. Frequency dependences of reflectance in the 12th diffraction order for rectangular, triangular, and trapezoidal diffraction gratings are calculated. It is shown that the maximum reflectance of the waveguide mode is attained using a rectangular or trapezoidal grating {approx}2 {mu}m deep in the laser structure. Deep trapezoidal diffraction gratings with large periods are fabricated in the Al{sub 0.3}Ga{sub 0.7}As cladding layer of a GaAs/AlGaAs laser structure using photolithography and reactive ion etching.

  1. Optical-feedback semiconductor laser Michelson interferometer for displacement measurements with directional discrimination.

    PubMed

    Rodrigo, P J; Lim, M; Saloma, C

    2001-02-01

    An optical-feedback semiconductor laser Michelson interferometer (OSMI) is presented for measuring microscopic linear displacements without ambiguity in the direction of motion. The two waves from the interferometer arms, one from the reference mirror and the other from the reflecting moving target, are fed back into the lasing medium (lambda = 830 nm), causing variations in the laser output power. We model the OSMI into an equivalent Fabry-Perot resonator and derive the dependence of the output power (and the junction voltage) on the path difference between the two interferometer arms. Numerical and experimental results consistently show that the laser output power varies periodically (period, lambda/2) with path difference. The output power variation exhibits an asymmetric behavior with the direction of motion, which is used to measure, at subwavelength resolution, the displacement vector (both amplitude and direction) of the moving sample. Two samples are considered in the experiments: (i) a piezoelectric transducer and (ii) an audio speaker.

  2. Four-wave mixing analysis on injection-locked quantum dot semiconductor lasers.

    PubMed

    Lin, Chih-Hao; Lin, Fan-Yi

    2013-09-09

    We derive a simplified rate equation model for the four-wave mixing (FWM) analysis on quantum dot (QD) semiconductor lasers subject to optical injection. The regenerative and the amplitude modulation spectra of the FWM signals with different intrinsic laser parameters and external injection conditions are investigated. By curve fitting the regenerative and the amplitude modulation spectra obtained experimentally, the intrinsic parameters of a commercial single-mode QD laser under different injection conditions are extracted. The linewidth enhancement factor α at different injection levels and detunings are shown, where a reduction of up to 39% from its free-running value is demonstrated. By increasing the injection strength, the α can be further reduced to minimized the chirp in optical communications.

  3. Quantum effect on modulational instability of laser radiation in a semiconductor plasma

    SciTech Connect

    Amin, M. R.

    2010-01-15

    Modulational instability of a high power laser radiation in a homogeneous unmagnetized piezoelectric semiconductor plasma has been investigated analytically. The fluid equations of quantum hydrodynamics coupled with the Maxwell's equations have been employed to find the nonlinear response of electrons in the piezoelectric semiconductor. The analysis is carried out through the derivation of the nonlinear dispersion relation for the four-wave modulational instability. An expression for the growth rate of the instability including the quantum effect due to Bohm potential has been obtained from the nonlinear dispersion relation. The quantum effect is observed to play a vital role in the four-wave scattering process. For a particular set of parameters, the quantum effect enhances the growth rate of the modulational instability by 37% compared to the growth rate predicted by the classical theory.

  4. Stimulated Brillouin scattering of laser in semiconductor plasma embedded with nano-sized grains

    NASA Astrophysics Data System (ADS)

    Sharma, Giriraj; Dad, R. C.; Ghosh, S.

    2015-07-01

    A high power laser propagating through semiconductor plasma undergoes Stimulated Brillouin scattering (SBS) from the electrostrictively generated acoustic perturbations. We have considered that nano-sized grains (NSGs) ions are embedded in semiconductor plasma by means of ion implantation. The NSGs are bombarded by the surrounding plasma particles and collect electrons. By considering a negative charge on the NSGs, we present an analytically study on the effects of NSGs on threshold field for the onset of SBS and Brillouin gain of generated Brillouin scattered mode. It is found that as the charge on the NSGs builds up, the Brillouin gain is significantly raised and the threshold pump field for the onset of SBS process is lowered.

  5. Stimulated Brillouin scattering of laser in semiconductor plasma embedded with nano-sized grains

    SciTech Connect

    Sharma, Giriraj; Dad, R. C.; Ghosh, S.

    2015-07-31

    A high power laser propagating through semiconductor plasma undergoes Stimulated Brillouin scattering (SBS) from the electrostrictively generated acoustic perturbations. We have considered that nano-sized grains (NSGs) ions are embedded in semiconductor plasma by means of ion implantation. The NSGs are bombarded by the surrounding plasma particles and collect electrons. By considering a negative charge on the NSGs, we present an analytically study on the effects of NSGs on threshold field for the onset of SBS and Brillouin gain of generated Brillouin scattered mode. It is found that as the charge on the NSGs builds up, the Brillouin gain is significantly raised and the threshold pump field for the onset of SBS process is lowered.

  6. Monte Carlo modeling of the dual-mode regime in quantum-well and quantum-dot semiconductor lasers.

    PubMed

    Chusseau, Laurent; Philippe, Fabrice; Disanto, Filippo

    2014-03-10

    Monte Carlo markovian models of a dual-mode semiconductor laser with quantum well (QW) or quantum dot (QD) active regions are proposed. Accounting for carriers and photons as particles that may exchange energy in the course of time allows an ab initio description of laser dynamics such as the mode competition and intrinsic laser noise. We used these models to evaluate the stability of the dual-mode regime when laser characteristics are varied: mode gains and losses, non-radiative recombination rates, intraband relaxation time, capture time in QD, transfer of excitation between QD via the wetting layer... As a major result, a possible steady-state dual-mode regime is predicted for specially designed QD semiconductor lasers thereby acting as a CW microwave or terahertz-beating source whereas it does not occur for QW lasers.

  7. Semiconductor laser's on-line coherence calibration and testing of frequency stability

    NASA Astrophysics Data System (ADS)

    Zakharov, Yu. N.; Popov, A. Yu.; Tyurin, A. V.

    2008-05-01

    One of the main constituent parts of optical coherent measuring apparatus is laser as source with stable performance of frequency, radiation intensity, and light beam uniformity. At present time semiconductor lasers are rather attractive devices in view of there low prices, small size, serviceability. Progress in its quality leads to including them not only in lightheads, but as lighting unit in measuring apparatus. In order to guarantee accuracy of measuring instruments, all parts of them must have stable performance, and in this respect semiconductor laser demand stabilization more that one characteristic quantity at once. And frequency stability on the one hand is overwhelmingly important for constancy of optical measuring instruments, on the other hand our investigations show that its regulatory control is very arduous task. Both holographic methods and phase modulated speckle interferometry clearly recognize smooth frequency shift and frequency jumping depending on pumping current and temperature. And for repeatability it's required to return both of them. So it is necessary laser frequency testing during working. For interferometric comparison circuit it is frequency variation that exerts influence on fringes pattern generation, so just this parameter should be traced in the course of measuring. Specially prepared test object, introduced in holographic scheme, allows to uncover frequency variation, if they had have place, and to reproduce coherence function of laser source. Complicated coherence function of semiconductor lasers can destroy interference pattern or foul the interpretation of it. So this coherence calibration is also very useful for results validity. Phase modulated speckle interferometry method allows to build phase correlation portraits, analogical to interferograms, hence multiwavelength contour generation masks the picture of intrinsic object information too. Both real wavelength change and nonresolution area, when coherence length is less

  8. Tantalum-based semiconductors for solar water splitting.

    PubMed

    Zhang, Peng; Zhang, Jijie; Gong, Jinlong

    2014-07-07

    Solar energy utilization is one of the most promising solutions for the energy crises. Among all the possible means to make use of solar energy, solar water splitting is remarkable since it can accomplish the conversion of solar energy into chemical energy. The produced hydrogen is clean and sustainable which could be used in various areas. For the past decades, numerous efforts have been put into this research area with many important achievements. Improving the overall efficiency and stability of semiconductor photocatalysts are the research focuses for the solar water splitting. Tantalum-based semiconductors, including tantalum oxide, tantalate and tantalum (oxy)nitride, are among the most important photocatalysts. Tantalum oxide has the band gap energy that is suitable for the overall solar water splitting. The more negative conduction band minimum of tantalum oxide provides photogenerated electrons with higher potential for the hydrogen generation reaction. Tantalates, with tunable compositions, show high activities owning to their layered perovskite structure. (Oxy)nitrides, especially TaON and Ta3N5, have small band gaps to respond to visible-light, whereas they can still realize overall solar water splitting with the proper positions of conduction band minimum and valence band maximum. This review describes recent progress regarding the improvement of photocatalytic activities of tantalum-based semiconductors. Basic concepts and principles of solar water splitting will be discussed in the introduction section, followed by the three main categories regarding to the different types of tantalum-based semiconductors. In each category, synthetic methodologies, influencing factors on the photocatalytic activities, strategies to enhance the efficiencies of photocatalysts and morphology control of tantalum-based materials will be discussed in detail. Future directions to further explore the research area of tantalum-based semiconductors for solar water splitting

  9. Development of lead salt semiconductor lasers for the 9-17 micron spectral region

    NASA Technical Reports Server (NTRS)

    Linden, K. J.; Butler, J. F.; Nill, K. W.; Reeder, R. E.

    1981-01-01

    Improved diode lasers of Pb sub 1-x Sn sub x Se operating in the 9-17 micrometers spectral region were developed. The performance characteristics of the best lasers exceeded the contract goals of 500 microW/mode at T 30K in the 9-12 micrometers region and 200 microW/mode at T 18K in the 16-17 micrometers region. Increased reliability and device yields resulted from processing improvements which evolved from a series of diagnostic studies. By means of Auger electron spectroscopy, laser shelf storage degradation was shown to be characterized by the presence of In metal on the semiconductor crystal surfaces. Studies of various metal barrier layers between the crystals and the In metal led to the development of an improved metallurgical contacting technology which has resulted in devices with performance stability values exceeding the contract goal of a one year shelf life. Lasers cycled over 500 times between 300K and 77K were also shown to be stable. Studies on improved methods of fabricating striped geometry lasers indicated that good spectral mode characteristics resulted from lasers which stripe widths of 12 and 25 micrometers.

  10. Wavelength-tunable actively mode-locked erbium-doped fiber ring laser using a distributed feedback semiconductor laser as mode locker and tunable filter

    NASA Astrophysics Data System (ADS)

    Li, Shenping; Chan, K. T.

    1999-07-01

    A wavelength-tunable actively mode-locked erbium fiber ring laser was demonstrated using a distributed feedback semiconductor laser as an intensity mode locker and a tunable optical filter. Very stable optical pulse trains at gigabit repetition rates were generated using harmonica mode locking. The supermode noise was suppressed to 60 dB below the signal level and the root-mean-square timing jitter (0.45 kHz-1 MHz) was found to be about 1% of the pulse duration. A continuous wavelength tuning range of 1.8 nm was achieved by changing the semiconductor laser temperature from 11.4 to 30 °C.

  11. {100}<100> or 45.degree.-rotated {100}<100>, semiconductor-based, large-area, flexible, electronic devices

    SciTech Connect

    Goyal, Amit

    2012-05-15

    Novel articles and methods to fabricate the same resulting in flexible, {100}<100> or 45.degree.-rotated {100}<100> oriented, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  12. Semiconductor saturable absorber mirror passively Q-switched 2.97 μm fluoride fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Jianfeng; Luo, Hongyu; He, Yulian; Liu, Yong; Luo, Binbin; Sun, Zhongyuan; Zhang, Lin; Turitsyn, Sergei K.

    2014-05-01

    A diode-cladding-pumped mid-infrared passively Q-switched Ho3+-doped fluoride fiber laser using a reverse designed broad band semiconductor saturable mirror (SESAM) was demonstrated. Nonlinear reflectivity of the SESAM was measured using an in-house Yb3+-doped mode-locked fiber laser at 1062 nm. Stable pulse train was produced at a slope efficient of 12.1% with respect to the launched pump power. Maximum pulse energy of 6.65 μJ with a pulse width of 1.68 μs and signal to noise ratio (SNR) of ~50 dB was achieved at a repetition rate of 47.6 kHz and center wavelength of 2.971 μm. To the best of our knowledge, this is the first 3 μm region SESAM based Q-switched fiber laser with the highest average power and pulse energy, as well as the longest wavelength from mid-infrared passively Q-switched fluoride fiber lasers.

  13. Semiconductor saturable absorber mirror passively Q-switched 2.97 μm fluoride fiber laser

    NASA Astrophysics Data System (ADS)

    Li, J. F.; Luo, H. Y.; He, Y. L.; Liu, Y.; Zhang, L.; Zhou, K. M.; Rozhin, A. G.; Turistyn, S. K.

    2014-06-01

    A diode-cladding-pumped mid-infrared passively Q-switched Ho3+-doped fluoride fiber laser using a reverse designed broad band semiconductor saturable mirror (SESAM) was demonstrated. Nonlinear reflectivity of the SESAM was measured using an in-house Yb3+-doped mode-locked fiber laser at 1062 nm. Stable pulse train was produced at a slope efficient of 12.1% with respect to the launched pump power. Maximum pulse energy of 6.65 µJ with a pulse width of 1.68 µs and signal-to-noise ratio (SNR) of ~50 dB was achieved at a repetition rate of 47.6 kHz and center wavelength of 2.971 µm. To the best of our knowledge, this is the first 3 µm region SESAM-based Q-switched fiber laser with the highest average power and pulse energy, as well as the longest wavelength from mid-infrared passively Q-switched fluoride fiber lasers.

  14. Theoretical modeling of the dynamics of a semiconductor laser subject to double-reflector optical feedback

    NASA Astrophysics Data System (ADS)

    Bakry, A.; Abdulrhmann, S.; Ahmed, M.

    2016-06-01

    We theoretically model the dynamics of semiconductor lasers subject to the double-reflector feedback. The proposed model is a new modification of the time-delay rate equations of semiconductor lasers under the optical feedback to account for this type of the double-reflector feedback. We examine the influence of adding the second reflector to dynamical states induced by the single-reflector feedback: periodic oscillations, period doubling, and chaos. Regimes of both short and long external cavities are considered. The present analyses are done using the bifurcation diagram, temporal trajectory, phase portrait, and fast Fourier transform of the laser intensity. We show that adding the second reflector attracts the periodic and perioddoubling oscillations, and chaos induced by the first reflector to a route-to-continuous-wave operation. During this operation, the periodic-oscillation frequency increases with strengthening the optical feedback. We show that the chaos induced by the double-reflector feedback is more irregular than that induced by the single-reflector feedback. The power spectrum of this chaos state does not reflect information on the geometry of the optical system, which then has potential for use in chaotic (secure) optical data encryption.

  15. Radio-over-fiber DSB-to-SSB conversion using semiconductor lasers at stable locking dynamics.

    PubMed

    Hsieh, Kun-Lin; Hung, Yu-Han; Hwang, Sheng-Kwang; Lin, Chien-Chung

    2016-05-02

    In radio-over-fiber systems, optical single-sideband (SSB) modulation signals are preferred to optical double-sideband (DSB) modulation signals for fiber distribution in order to mitigate the microwave power fading effect. However, typically adopted modulation schemes generate DSB signals, making DSB-to-SSB conversion necessary before or after fiber distribution. This study investigates a semiconductor laser at stable locking dynamics for such conversion. The conversion relies solely on the nonlinear dynamical interaction between an input DSB signal and the laser. Only a typical semiconductor laser is therefore required as the key conversion unit, and no pump or probe signal is necessary. The conversion can be achieved for a broad tunable range of microwave frequency up to at least 60 GHz. In addition, the conversion can be carried out even when the microwave frequency, the power of the input DSB signal, or the frequency of the input DSB signal fluctuates over a wide range, leading to high adaptability and stability of the conversion system. After conversion, while the microwave phase quality, such as linewidth and phase noise, is mainly preserved, a bit-error ratio down to 10-9 is achieved for a data rate up to at least 8 Gb/s with a detection sensitivity improvement of more than 1.5 dB.

  16. Nanophotonics Based on Semiconductor-Photonic Crystal/Quantum Dot and Metal-/Semiconductor-Plasmonics

    NASA Astrophysics Data System (ADS)

    Asakawa, Kiyoshi; Sugimoto, Yoshimasa; Ikeda, Naoki; Tsuya, Daiju; Koide, Yasuo; Watanabe, Yoshinori; Ozaki, Nobuhiko; Ohkouchi, Shunsuke; Nomura, Tsuyoshi; Inoue, Daisuke; Matsui, Takayuki; Miura, Atsushi; Fujikawa, Hisayoshi; Sato, Kazuo

    This paper reviews our recent activities on nanophotonics based on a photonic crystal (PC)/quantum dot (QD)-combined structure for an all-optical device and a metal/semiconductor composite structure using surface plasmon (SP) and negative refractive index material (NIM). The former structure contributes to an ultrafast signal processing component by virtue of new PC design and QD selective-area-growth technologies, while the latter provides a new RGB color filter with a high precision and optical beam-steering device with a wide steering angle.

  17. Ultrafast laser trimming for reduced device leakage in high performance OTFT semiconductors for flexible displays

    NASA Astrophysics Data System (ADS)

    Karnakis, Dimitris; Cooke, Michael D.; Chan, Y. F.; Ogier, Simon D.

    2013-03-01

    Organic semiconductors (OSC) are solution processable synthetic materials with high carrier mobility that promise to revolutionise flexible electronics manufacturing due to their low cost, lightweight and high volume low temperature printing in reel-to-reel (R2R) [1] for applications such as flexible display backplanes (Fig.1), RFID tags, and logic/memory devices. Despite several recent technological advances, organic thin film transistor (OTFT) printing is still not production-ready due to limitations mainly with printing resolution on dimensionally unstable substrates and device leakage that reduces dramatically electrical performance. OTFTs have the source-drain in ohmic contact with the OSC material to lower contact resistance. If they are unpatterned, a leakage pathway from source to drain develops which results in non-optimum on/off currents and not controllable device uniformity (Fig.2). DPSS lasers offer several key advantages for OTFT patterning including maskless, non-contact, dry patterning, scalable large area operation with precision registration, well-suited to R2R manufacturing at overall μm size resolutions. But the thermal management of laser processing is very important as the devices are very sensitive to heat and thermomechanical damage [2]. This paper discusses 343nm picosecond laser ablation trimming of 50nm thick PTAA, TIPS pentacene and other semiconductor compounds on thin 50nm thick metal gold electrodes in a top gate configuration. It is shown that with careful optimisation, a suitable process window exists resulting in clean laser structuring without damage to the underlying layers while also containing laser debris. Several order of magnitude improvements were recorded in on/off currents up to 106 with OSC mobilities of 1 cm2/Vsec, albeit at slightly higher than optimum threshold voltages which support demanding flexible display backplane applications.

  18. Analytical predictions of the temperature profile within semiconductor nanostructures for solid-state laser refrigeration

    NASA Astrophysics Data System (ADS)

    Smith, Bennett E.; Zhou, Xuezhe; Davis, E. James; Pauzauskie, Peter J.

    2016-03-01

    The laser refrigeration of solid-state materials with nanoscale dimensions has been demonstrated for both semi- conducting (cadmium sulfide, CdS) and insulating dielectrics (Yb:YLiF4, YLF) in recent years. During laser refrigeration it is possible to observe morphology dependent resonances (MDRs), analogous to what is well- known in classical (Mie) light scattering theory, when the characteristic dimensions of the nanostructure are comparable to the wavelength of light used to initiate the laser cooling process. Mie resonances can create substantial increases for internal optical fields within a given nanostructure with the potential to enhance the absorption efficiency at the beginning of the cooling cycle. Recent breakthroughs in the laser refrigeration of semiconductor nanostructures have relied on materials that exhibit rectangular symmetry (nanoribbons). Here, we will present recent analytical, closed-form solutions to the energy partial differential equation that can be used to calculate the internal spatial temperature profile with a given semiconductor nanoribbon during irradiation by a continuous-wave laser. First, the energy equation is made dimensionless through the substitution of variables before being solved using the classical separation-of-variables approach. In particular, calculations will be presented for chalcogenide (CdS) nanoribbons using a pump wavelength of 1064 nm. For nanostructures with lower symmetry (such as YLF truncated tetragonal bipyramids) it is also possible to observe MDRs through numerical simulations using either the discrete dipole approximation or finite-difference time-domain simulations, and the resulting temperature profile can be calculated using the finite element method. Theoretical predictions are presented using parameters that will allow comparison with experimental data in the near future.

  19. Experiment on synchronization of semiconductor lasers by common injection of constant-amplitude random-phase light.

    PubMed

    Aida, Hiroki; Arahata, Masaya; Okumura, Haruka; Koizumi, Hayato; Uchida, Atsushi; Yoshimura, Kazuyuki; Muramatsu, Jun; Davis, Peter

    2012-05-21

    We experimentally and numerically observe the synchronization between two semiconductor lasers induced by common optical injection with constant-amplitude and random-phase modulation in configurations with and without optical feedback. Large cross correlation (~0.9) between the intensity oscillations of the two response lasers can be achieved although the correlation between the drive laser and either one of the two response lasers is very small (~0.2). High quality synchronization is achieved in the presence of optical feedback in response lasers with matched feedback phase offset. We investigate the dependence of synchronization on parameter values over wide parameter ranges.

  20. Transition from unidirectional to delayed bidirectional coupling in optically coupled semiconductor lasers.

    PubMed

    Bonatto, Cristian; Kelleher, Bryan; Huyet, Guillaume; Hegarty, Stephen P

    2012-02-01

    We investigate the transition from unidirectional to delayed bidirectional coupling of semiconductor lasers. By tuning the coupling strength in one direction we show how the locking region evolves as a function of the detuning and coupling strength. We consider two representative values of the relaxation oscillation damping: one where the relaxation oscillations are very underdamped and one where they are very overdamped. Qualitatively different dynamical scenarios are shown to emerge for each case. Several features of the delayed bidirectional system can be seen as remaining from the unidirectional system while others clearly arise due to the delayed coupling and are similar to effects seen in delayed feedback configurations.

  1. InGaZnO semiconductor thin film fabricated using pulsed laser deposition.

    PubMed

    Chen, Jiangbo; Wang, Li; Su, Xueqiong; Kong, Le; Liu, Guoqing; Zhang, Xinping

    2010-01-18

    The InGaZnO thin films are fabricated on the quartz glass using pulsed laser deposition (PLD), where the target is prepared by mixing the Ga(2)O(3), In(2)O(3), and ZnO powders at a mol ratio of 1:1:8 before the solid-state reactions in a tube furnace at the atmospheric pressure. The product thin films were characterized comprehensively by X-ray diffraction, atomic force microscopy, Hall-effect investigation, and X-ray photoelectron spectroscopy. Thus, we demonstrate semiconductor thin-film materials with high smoothness, high transmittance in visible region, and excellent electrical properties.

  2. Equivalent circuit theory of spontaneous emission power in semiconductor laser optical amplifiers

    NASA Astrophysics Data System (ADS)

    Chu, James Chi-Yin; Ghafouri-Shiraz, H.

    1994-05-01

    An equivalent circuit model for a semiconductor laser amplifier (SLA) has been developed. This model can be used with a transfer matrix method (TMM) to analyze the performance of a SLA. The validity of the model is explored in this paper by analyzing the spontaneous emission noise power in a Fabry-Perot SLA with a uniform distribution of material gain coefficient. The result is found to be identical with that derived by the Green function approach. The physical reasons for the validity of the equivalent circuit model are also discussed, and possible further applications of the model are suggested.

  3. Semiconductor laser having a non-absorbing passive region with beam guiding

    NASA Technical Reports Server (NTRS)

    Botez, Dan (Inventor)

    1986-01-01

    A laser comprises a semiconductor body having a pair of end faces and including an active region comprising adjacent active and guide layers which is spaced a distance from the end face and a passive region comprising adjacent non-absorbing guide and mode control layers which extends between the active region and the end face. The combination of the guide and mode control layers provides a weak positive index waveguide in the lateral direction thereby providing lateral mode control in the passive region between the active region and the end face.

  4. Reduction of semiconductor laser diode phase and amplitude noise in interferometric fiber optic sensors.

    PubMed

    Newson, T P; Farahi, F; Jones, J D; Jackson, D A

    1989-10-01

    An optical configuration employing two conventional Michelson interferometers and a fiber Fabry-Perot interferometer connected in parallel is used to demonstrate the principle of common mode rejection of both the amplitude and frequency noise of a semiconductor laser. Common mode noise rejection is maximized when the outputs of the two interferometers with matched path imbalance, fringe visibility and amplitude are differentially combined. One interferometer is used as a reference, and the other as a sensing interferometer. The fiber Fabry-Perot interferometer is used as the sensing interferometer and is demonstrated as a miniature acoustic sensing element.

  5. Femtosecond superradiance in semiconductor lasers: anomalous internal second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Vasil'ev, P. P.; Putilin, A. N.; Sergeev, A. B.

    2016-10-01

    The emission of anomalously bright blue light under internal doubling of the frequency of femtosecond superradiance pulses in the active medium of semiconductor GaAs/AlGaAs laser heterostructures has been experimentally found. The efficiency of the internal second-harmonic generation is an order of magnitude higher than in the conventional lasing regime. This effect is due to the formation of a transient ordered state of electrons and holes under superradiance, occurrence of dynamic coherent population lattices, and periodic modulation of the nonlinear susceptibility of the medium.

  6. Research on laser fuze technology based on MEMS/MOEMS

    NASA Astrophysics Data System (ADS)

    Chen, Huimin; Li, Ping; Zhang, Yingwen; Li, Kun; Sun, Jianqiang

    2007-12-01

    With the development of semiconductor laser technology, laser proximity fuzes have been widely used in various kinds of guided missiles and conventional ammunitions. Conventional laser proximity fuzes consisting of separated components, have the disadvantages such as large volumes and poor anti-jamming abilities, so are not satisfied with the modern warfare circumstances. Combined with the separated components, the system has been divided into transmitting module, receiving module and information processing module, the different modules have been analyzed in detail,. Meanwhile, the transmitting driven circuit has been developed and laser pulse with 20ns narrow width was obtained. In order to meet the multifunction and miniaturization, laser fuzes based on MEMS/MOEMS have been introduced in this paper. Technologies include vertical-cavity surface-emitting laser, integrated resonant-cavity photodetector and refractive micro-optics. The entire structure was roughly 1~2mm thick and 1mm on a side.

  7. Cu2O-based solar cells using oxide semiconductors

    NASA Astrophysics Data System (ADS)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2016-01-01

    We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO (AZO)/n-type oxide semiconductor/p-type Cu2O heterojunction solar cells fabricated using p-type Cu2O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu2O sheets under various deposition conditions using a pulsed laser deposition method. In Cu2O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa2O4 thin-film layer. In most of the Cu2O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO-MgO and Ga2O3-Al2O3 systems, higher conversion efficiencies (η) as well as a high open circuit voltage (Voc) were obtained by using a relatively small amount of MgO or Al2O3, e.g., (ZnO)0.91-(MgO)0.09 and (Ga2O3)0.975-(Al2O3)0.025, respectively. When Cu2O-based heterojunction solar cells were fabricated using Al2O3-Ga2O3-MgO-ZnO (AGMZO) multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high Voc of 0.98 V and an η of 4.82% were obtained. In addition, an enhanced η and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu2O heterojunction solar cells fabricated using Na-doped Cu2O (Cu2O:Na) sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an η of 6.25% and a Voc of 0.84 V were obtained in a MgF2/AZO/n-(Ga2O3-Al2O3)/p-Cu2O:Na heterojunction solar cell fabricated using a Cu2O:Na sheet with a resistivity of approximately 10 Ω·cm and a (Ga0.975Al0

  8. Rare Earth Doped Semiconductors for Phosphors and Lasers

    DTIC Science & Technology

    2005-10-17

    Judd - Ofelt analysis and reported branching ratios of less than ~1% for the 1D2 1G4 and 1G4 3F2 transi- tions [8,9]. A slightly higher...the GaN host matrix . Several studies have recently appeared focusing on the preparation and optical properties of GaN:Eu.4–11 Based on the comparison...similar explanation was recently proposed for the poor above-gap excitation efficiency of Tb3 + ions in GaN:Tb [9]. In an effort to optimize the carrier

  9. High temperature heat source generation with quasi-continuous wave semiconductor lasers at power levels of 6 W for medical use.

    PubMed

    Fujimoto, Takahiro; Imai, Yusuke; Tei, Kazuyoku; Ito, Shinobu; Kanazawa, Hideko; Yamaguchi, Shigeru

    2014-01-01

    We investigate a technology to create a high temperature heat source on the tip surface of the glass fiber proposed for medical surgery applications. Using 4 to 6 W power level semiconductor lasers at a wavelength of 980 nm, a laser coupled fiber tip was preprocessed to contain a certain amount of titanium oxide powder with a depth of 100 μm from the tip surface so that the irradiated low laser energy could be perfectly absorbed to be transferred to thermal energy. Thus, the laser treatment can be performed without suffering from any optical characteristic of the material. A semiconductor laser was operated quasi-continuous wave mode pulse time duration of 180 ms and >95% of the laser energy was converted to thermal energy in the fiber tip. Based on two-color thermometry, by using a gated optical multichannel analyzer with a 0.25 m spectrometer in visible wavelength region, the temperature of the fiber tip was analyzed. The temperature of the heat source was measured to be in excess 3100 K.

  10. Uniform Doping in Quantum-Dots-Based Dilute Magnetic Semiconductor.

    PubMed

    Saha, Avijit; Shetty, Amitha; Pavan, A R; Chattopadhyay, Soma; Shibata, Tomohiro; Viswanatha, Ranjani

    2016-07-07

    Effective manipulation of magnetic spin within a semiconductor leading to a search for ferromagnets with semiconducting properties has evolved into an important field of dilute magnetic semiconductors (DMS). Although a lot of research is focused on understanding the still controversial origin of magnetism, efforts are also underway to develop new materials with higher magnetic temperatures for spintronics applications. However, so far, efforts toward quantum-dots(QDs)-based DMS materials are plagued with problems of phase separation, leading to nonuniform distribution of dopant ions. In this work, we have developed a strategy to synthesize highly crystalline, single-domain DMS system starting from a small magnetic core and allowing it to diffuse uniformly inside a thick CdS semiconductor matrix and achieve DMS QDs. X-ray absorption fine structure (XAFS) spectroscopy and energy-dispersive X-ray spectroscopy-scanning transmission electron microscopy (STEM-EDX) indicates the homogeneous distribution of magnetic impurities inside the semiconductor QDs leading to superior magnetic property. Further, the versatility of this technique was demonstrated by obtaining ultra large particles (∼60 nm) with uniform doping concentration as well as demonstrating the high quality magnetic response.

  11. Laser-powered lunar base

    NASA Technical Reports Server (NTRS)

    Costen, R.; Humes, Donald H.; Walker, G. H.; Williams, M. D.; Deyoung, Russell J.

    1989-01-01

    The objective was to compare a nuclear reactor-driven Sterling engine lunar base power source to a laser-to-electric converter with orbiting laser power station, each providing 1 MW of electricity to the lunar base. The comparison was made on the basis of total mass required in low-Earth-orbit for each system. This total mass includes transportation mass required to place systems in low-lunar orbit or on the lunar surface. The nuclear reactor with Sterling engines is considered the reference mission for lunar base power and is described first. The details of the laser-to-electric converter and mass are discussed. The next two solar-driven high-power laser concepts, the diode array laser or the iodine laser system, are discussed with associated masses in low-lunar-orbit. Finally, the payoff for laser-power beaming is summarized.

  12. Pulsed-CO2-laser-induced damage mechanisms in semiconductors

    NASA Astrophysics Data System (ADS)

    Lefranc, Sebastian; Autric, Michel L.

    1998-09-01

    Laser irradiation induced damage to several materials of interest for use as 10.6 micrometer laser system windows and lenses is investigated in this paper. The irradiation source in these single shot experiments was a pulsed TEA CO2 laser (lambda equals 10.6 micrometer, (tau) pulse equals 3.5 microsecond, I equals 1 - 100 MW/cm2 onto the sample). A time resolved study of the damage process in semiconductors (Ge, ZnSe, ZnS) has been carried out during the interaction by measuring the variation of the transmitted and reflected intensity of a CO2 cw laser through the samples. An analysis of the pulse shape dependence on the damage parameters has been investigated. Results show that damages are initiated by the high power peak of the laser pulse on both surfaces and in the bulk of the materials. The damaged materials have been characterized for various incident fluences by means of optical microscopy and scanning electron microscopy in terms of morphology.

  13. Semiconductor laser diode array characterization by means of field intensity measurements

    NASA Astrophysics Data System (ADS)

    Zeni, Luigi; Cutolo, Antonello; Pierri, Rocco

    1999-04-01

    Semiconductor laser diode arrays are becoming a widespread source for a large variety of applications, ranging from telecommunications to industry. In particular, the availability of low-cost high-power laser diode arrays makes it possible their use in industrial context for material cutting, welding, diagnostics and processing. In the above applications the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. We have developed a characterization technique which, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The importance of this approach is twofold. First it allows a non destructive quality control on ready-to-use laser arrays; second it may represent a powerful tool for the detection of design problems in the array itself and in the bias circuitry as well. The problem is formulated as an inverse one and the solution is found by minimizing a proper functional. Several numerical experiments have been performed and the results clearly indicate the ability of the proposed approach tin identifying specific failures in a laser diode array, such as single element power drop.

  14. Method of plasma etching Ga-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2012-12-25

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

  15. Narrow linewidth broadband tunable semiconductor laser at 840 nm with dual acousto-optic tunable configuration for OCT applications

    NASA Astrophysics Data System (ADS)

    Chamorovskiy, Alexander; Shramenko, Mikhail V.; Lobintsov, Andrei A.; Yakubovich, Sergei D.

    2016-03-01

    We demonstrate a tunable narrow linewidth semiconductor laser for the 840 nm spectral range. The laser has a linear cavity comprised of polarization maintaining (PM) fiber. A broadband semiconductor optical amplifier (SOA) in in-line fiber-coupled configuration acts as a gain element. It is based on InGaAs quantum-well (QW) active layer. SOA allows for tuning bandwidth exceeding 25 nm around 840 nm. Small-signal fiber-to-fiber gain of SOA is around 30 dB. A pair of acousto-optic tunable filters (AOTF) with a quasi-collinear interaction of optical and acoustic waves are utilized as spectrally selective elements. AOTF technology benefits in continuous tuning, broadband operation, excellent reproducibility and stability of the signal, as well as a high accuracy of wavelength selectivity due to the absence of mechanically moving components. A single AOTF configuration has typical linewidth in 0.05-0.15 nm range due to a frequency shift obtained during each roundtrip. A sequential AOTF arrangement enables instantaneous linewidth generation of <0.01 nm by compensating for this shift. Linewidth as narrow as 0.0036 nm is observed at 846 nm wavelength using a scanning Fabry-Perot interferometer with 50 MHz spectral resolution. Output power is in the range of 1 mW. While the majority of commercial tunable sources operate in 1060-1550 nm spectral ranges, the 840 nm spectral range is beneficial for optical coherence tomography (OCT). The developed narrow linewidth laser can be relevant for OCT with extended imaging depth, as well as spectroscopy, non-destructive testing and other applications.

  16. Real-time frequency dynamics and high-resolution spectra of a semiconductor laser with delayed feedback

    PubMed Central

    Brunner, Daniel; Porte, Xavier; Soriano, Miguel C.; Fischer, Ingo

    2012-01-01

    The unstable emission of semiconductor lasers due to delayed optical feedback is characterized by combined intensity and frequency dynamics. Nevertheless, real-time experimental investigations have so far been restricted to measurements of intensity dynamics only. Detailed analysis and comparison with numerical models, therefore, have suffered from limited experimental information. Here, we report the simultaneous determination of the lasers optical emission intensity and emission frequency with high temporal resolution. The frequency dynamics is made accessible using a heterodyne detection scheme, in which a beat signal between the delayed feedback laser and a reference laser is generated. Our experiment provides insight into the overall spectral drift on nanosecond timescales, the spectral distribution of the unstable pulsations and the role of the individual external cavity modes. This opens new perspectives for the analysis, understanding and functional utilization of delayed feedback semiconductor lasers. PMID:23066501

  17. Efficient holmium:yttrium lithium fluoride laser longitudinally pumped by a semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1987-01-01

    Optical pumping of a holmium:yttrium lithium floride (Ho:YLF) crystal with a 790-nm continuous-wave diode-laser array has generated 56 mW of 2.1-micron laser radiation with an optical-to-optical conversion slope efficiency of 33 percent while the crystal temperature is held at 77 K. The lasing threshold occurs at 7 mW of input power, and laser operation continues up to a crystal temperature of 124 K.

  18. Semiconductor ring lasers subject to both on-chip filtered optical feedback and external conventional optical feedback

    NASA Astrophysics Data System (ADS)

    Khoder, Mulham; Van der Sande, Guy; Danckaert, Jan; Verschaffelt, Guy

    2016-05-01

    It is well known that the performance of semiconductor lasers is very sensitive to external optical feedback. This feedback can lead to changes in lasing characteristics and a variety of dynamical effects including chaos and coherence collapse. One way to avoid this external feedback is by using optical isolation, but these isolators and their packaging will increase the cost of the total system. Semiconductor ring lasers nowadays are promising sources in photonic integrated circuits because they do not require cleaved facets or mirrors to form a laser cavity. Recently, some of us proposed to combine semiconductor ring lasers with on chip filtered optical feedback to achieve tunable lasers. The feedback is realized by employing two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifier gates are used to control the feedback strength. In this work, we investigate how such lasers with filtered feedback are influenced by an external conventional optical feedback. The experimental results show intensity fluctuations in the time traces in both the clockwise and counterclockwise directions due to the conventional feedback. We quantify the strength of the conventional feedback induced dynamics be extracting the standard deviation of the intensity fluctuations in the time traces. By using filtered feedback, we can shift the onset of the conventional feedback induced dynamics to larger values of the feedback rate [ Khoder et al, IEEE Photon. Technol. Lett. DOI: 10.1109/LPT.2016.2522184]. The on-chip filtered optical feedback thus makes the semiconductor ring laser less senstive to the effect of (long) conventional optical feedback. We think these conclusions can be extended to other types of lasers.

  19. Compact, temperature-stable multi-gigahertz passively modelocked semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Song, Yan-Rong; Guoyu, He-Yang; Zhang, Peng; Tian, Jin-Rong

    2015-08-01

    We present a compact passively mode-locked semiconductor disk laser at 1045 nm. The gain chip without any post processing consists of 16 compressively strained InGaAs symmetrical step quantum wells in the active region. 3-GHz repetition rate, 4.9-ps pulse duration, and 30-mW average output power are obtained with 1.4 W of 808-nm incident pump power. The temperature stability of the laser is demonstrated to have an ideal shift rate of 0.035 nm/K of the lasing wavelength. Project supported by the National Natural Science Foundation of China (Grant No. 61177047) and the Key Project of the National Natural Science Foundation of China (Grant No. 61235010).

  20. Manipulating coherence resonance in a quantum dot semiconductor laser via electrical pumping.

    PubMed

    Otto, Christian; Lingnau, Benjamin; Schöll, Eckehard; Lüdge, Kathy

    2014-06-02

    Excitability and coherence resonance are studied in a semiconductor quantum dot laser under short optical self-feedback. For low pump levels, these are observed close to a homoclinic bifurcation, which is in correspondence with earlier observations in quantum well lasers. However, for high pump levels, we find excitability close to a boundary crisis of a chaotic attractor. We demonstrate that in contrast to the homoclinic bifurcation the crisis and thus the excitable regime is highly sensitive to the pump current. The excitability threshold increases with the pump current, which permits to adjust the sensitivity of the excitable unit to noise as well as to shift the optimal noise strength, at which maximum coherence is observed. The shift adds up to more than one order of magnitude, which strongly facilitates experimental realizations.

  1. Modeling of millimeter-wave modulation characteristics of semiconductor lasers under strong optical feedback.

    PubMed

    Bakry, Ahmed

    2014-01-01

    This paper presents modeling and simulation on the characteristics of semiconductor laser modulated within a strong optical feedback (OFB-)induced photon-photon resonance over a passband of millimeter (mm) frequencies. Continuous wave (CW) operation of the laser under strong OFB is required to achieve the photon-photon resonance in the mm-wave band. The simulated time-domain characteristics of modulation include the waveforms of the intensity and frequency chirp as well as the associated distortions of the modulated mm-wave signal. The frequency domain characteristics include the intensity modulation (IM) and frequency modulation (FM) responses in addition to the associated relative intensity noise (RIN). The signal characteristics under modulations with both single and two mm-frequencies are considered. The harmonic distortion and the third order intermodulation distortion (IMD3) are examined and the spurious free dynamic range (SFDR) is calculated.

  2. Wavelength switchable semiconductor laser using half-wave V-coupled cavities.

    PubMed

    He, Jian-Jun; Liu, Dekun

    2008-03-17

    A new semiconductor laser structure with digitally switchable wavelength is proposed. The device comprises two coupled cavities with different optical path lengths, which form V-shaped branches with a reflective 2x2 half-wave optical coupler at the closed end. The reflective 2x2 coupler is designed to have a pi-phase difference between cross-coupling and self-coupling so as to produce synchronous power transfer functions. High single-mode selectivity is achieved by optimizing the coupling coefficient. The switchable wavelength range is greatly increased by using Vernier effect. Using deep-etched trenches as partial reflectors, additional waveguide branch structures are used outside the laser cavities to form a complete Mach-Zehnder interferometer, allowing space switching, variable attenuation, or high speed modulation to be realized simultaneously. Detailed design principle and numerical results are presented.

  3. Radio-over-fiber AM-to-FM upconversion using an optically injected semiconductor laser.

    PubMed

    Chan, Sze-Chun; Hwang, Sheng-Kwang; Liu, Jia-Ming

    2006-08-01

    A radio-over-fiber system uses light to carry a microwave subcarrier on optical fibers. The microwave is usually frequency modulated for wireless broadcasting. A conventional optical communication system usually operates at the baseband with amplitude modulation. The interface of the two systems thus needs an upconversion from the baseband to the microwave band with AM-to-FM transformation. An all-optical solution employing an optically injected semiconductor laser is investigated. The laser is operated in a dynamic state, where its intensity oscillates at a microwave frequency that varies with the injection strength. When the injection carries AM data, the microwave is frequency modulated accordingly. We demonstrate optical conversion from an OC-12 622-Mbps AM baseband signal to the corresponding FM microwave signal. The microwave is centered at 15.90 GHz. A bit-error rate of less than 10(-9) is measured.

  4. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode.

    PubMed

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus; Shen, Yuxin; Vanderheiden, Sylvia; Valouch, Sebastian; Vannahme, Christoph; Bräse, Stefan; Mappes, Timo; Lemmer, Uli

    2012-03-12

    The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured thickness profile. The laser threshold is low enough that inexpensive laser diodes can be used as pump sources.

  5. Semiconductor wire array structures, and solar cells and photodetectors based on such structures

    SciTech Connect

    Kelzenberg, Michael D.; Atwater, Harry A.; Briggs, Ryan M.; Boettcher, Shannon W.; Lewis, Nathan S.; Petykiewicz, Jan A.

    2014-08-19

    A structure comprising an array of semiconductor structures, an infill material between the semiconductor materials, and one or more light-trapping elements is described. Photoconverters and photoelectrochemical devices based on such structure also described.

  6. Physical layer one-time-pad data encryption through synchronized semiconductor laser networks

    NASA Astrophysics Data System (ADS)

    Argyris, Apostolos; Pikasis, Evangelos; Syvridis, Dimitris

    2016-02-01

    Semiconductor lasers (SL) have been proven to be a key device in the generation of ultrafast true random bit streams. Their potential to emit chaotic signals under conditions with desirable statistics, establish them as a low cost solution to cover various needs, from large volume key generation to real-time encrypted communications. Usually, only undemanding post-processing is needed to convert the acquired analog timeseries to digital sequences that pass all established tests of randomness. A novel architecture that can generate and exploit these true random sequences is through a fiber network in which the nodes are semiconductor lasers that are coupled and synchronized to central hub laser. In this work we show experimentally that laser nodes in such a star network topology can synchronize with each other through complex broadband signals that are the seed to true random bit sequences (TRBS) generated at several Gb/s. The potential for each node to access real-time generated and synchronized with the rest of the nodes random bit streams, through the fiber optic network, allows to implement an one-time-pad encryption protocol that mixes the synchronized true random bit sequence with real data at Gb/s rates. Forward-error correction methods are used to reduce the errors in the TRBS and the final error rate at the data decoding level. An appropriate selection in the sampling methodology and properties, as well as in the physical properties of the chaotic seed signal through which network locks in synchronization, allows an error free performance.

  7. Method of plasma etching GA-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2013-01-01

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

  8. Semiconductor Nanocrystals-Based White Light Emitting Diodes

    SciTech Connect

    Dai, Quanqin; Hu, Michael Z.; Duty, Chad E

    2010-01-01

    In response to the demands for energy and the concerns of global warming and climate change, energy efficient and environmentally friendly solid state lighting, such as white light emitting diodes (WLEDs), is considered to be the most promising and suitable light source. Because of their small size, high efficiency, and long lifetime, WLEDs based on colloidal semiconductor nanocrystals (or quantum dots) are emerging as a completely new technology platform for the development of flat-panel displays and solid state lighting, exhibiting the potential to replace the conventionally used incandescent and fluorescent lamps. This replacement could cut the ever-increasing energy consumption, solve the problem of rapidly depleting fossil fuel reserves, and improve the quality of the global environment. In this review, we highlight the recent progress in semiconductor nanocrystals-based WLEDs, compare different approaches for generating white light, and discuss the benefits and challenges of the solid state lighting technology.

  9. Semiconductor-Nanocrystals-Based White Light-Emitting Diodes

    SciTech Connect

    Dai, Quanqin; Duty, Chad E; Hu, Michael Z.

    2010-01-01

    In response to the demands for energy and the concerns of global warming and climate change, energy efficient and environmentally friendly solid-state lighting, such as white lightemitting diodes (WLEDs), is considered to be the most promising and suitable light source. Because of their small size, high efficiency, and long lifetime, WLEDs based on colloidal semiconductor nanocrystals (or quantum dots) are emerging as a completely new technology platform for the development of flat-panel displays and solid-state lighting, exhibiting the potential to replace the conventionally used incandescent and fluorescent lamps. This replacement can cut the ever-increasing level of energy consumption, solve the problem of rapidly depleting fossil fuel reserves, and improve the quality of the global environment. In this review, the recent progress in semiconductor-nanocrystals-based WLEDs is highlighted, the different approaches for generating white light are compared, and the benefits and challenges of the solid-state lighting technology are discussed.

  10. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Surface effects in laser diodes

    NASA Astrophysics Data System (ADS)

    Beister, G.; Maege, J.; Richter, G.

    1988-11-01

    Changes in the current-voltage characteristics below the threshold current were observed in gain-guided stripe laser diodes after preliminary lasing. This effect was not fully understood. Similar changes in the laser characteristics appeared as a result of etching in a gaseous medium. The observed changes were attributed tentatively to surface currents.

  11. Realization of III-V Semiconductor Periodic Nanostructures by Laser Direct Writing Technique

    NASA Astrophysics Data System (ADS)

    Huang, Yuan-qing; Huang, Rong; Liu, Qing-lu; Zheng, Chang-cheng; Ning, Ji-qiang; Peng, Yong; Zhang, Zi-yang

    2017-01-01

    In this paper, we demonstrated the fabrication of one-dimensional (1D) and two-dimensional (2D) periodic nanostructures on III-V GaAs substrates utilizing laser direct writing (LDW) technique. Metal thin films (Ti) and phase change materials (Ge2Sb2Te5 (GST) and Ge2Sb1.8Bi0.2Te5 (GSBT)) were chosen as photoresists to achieve small feature sizes of semiconductor nanostructures. A minimum feature size of about 50 nm about a quarter of the optical diffraction limit was obtained on the photoresists, and 1D III-V semiconductor nanolines with a minimum width of 150 nm were successfully acquired on the GaAs substrate which was smaller than the best results acquired on Si substrate ever reported. 2D nanosquare holes were fabricated as well by using Ti thin film as the photoresist, with a side width of about 200 nm, but the square holes changed to a rectangle shape when GST or GSBT was employed as the photoresist, which mainly resulted from the interaction of two cross-temperature fields induced by two scanning laser beams. The interacting mechanism of different photoresists in preparing periodic nanostructures with the LDW technique was discussed in detail.

  12. Influence of kinetic hole filling on the stability of mode-locked semiconductor disk lasers

    NASA Astrophysics Data System (ADS)

    Moloney, Jerome V.; Kilen, Isak; Hader, Jorg; Koch, Stephan W.

    2016-03-01

    Microscopic many-body theory is employed to analyze the mode-locking dynamics of a vertical external-cavity surface-emitting laser with a saturable absorber mirror. The quantum-wells are treated microscopically through the semiconductor Bloch equations and the light field using Maxwell's equations. Higher order correlation effects such as polarization dephasing and carrier relaxation at the second Born level are included and also approximated using effective rates fitted to second-Born-Markov evaluations. The theory is evaluated numerically for vertical external cavity surface emitting lasers with resonant periodic gain media. For given gain, the influence of the loss conditions on the very-short pulse generation in the range above 100 fs is analyzed. Optimized operational parameters are identified. Additionally, the fully microscopic theory at the second Born level is used to carrier out a pump-probe study of the carrier recovery in individual critical components of the VECSEL cavity such as the VECSEL chip itself and semiconductor or graphene saturable absorber mirrors.

  13. Realization of III-V Semiconductor Periodic Nanostructures by Laser Direct Writing Technique.

    PubMed

    Huang, Yuan-Qing; Huang, Rong; Liu, Qing-Lu; Zheng, Chang-Cheng; Ning, Ji-Qiang; Peng, Yong; Zhang, Zi-Yang

    2017-12-01

    In this paper, we demonstrated the fabrication of one-dimensional (1D) and two-dimensional (2D) periodic nanostructures on III-V GaAs substrates utilizing laser direct writing (LDW) technique. Metal thin films (Ti) and phase change materials (Ge2Sb2Te5 (GST) and Ge2Sb1.8Bi0.2Te5 (GSBT)) were chosen as photoresists to achieve small feature sizes of semiconductor nanostructures. A minimum feature size of about 50 nm about a quarter of the optical diffraction limit was obtained on the photoresists, and 1D III-V semiconductor nanolines with a minimum width of 150 nm were successfully acquired on the GaAs substrate which was smaller than the best results acquired on Si substrate ever reported. 2D nanosquare holes were fabricated as well by using Ti thin film as the photoresist, with a side width of about 200 nm, but the square holes changed to a rectangle shape when GST or GSBT was employed as the photoresist, which mainly resulted from the interaction of two cross-temperature fields induced by two scanning laser beams. The interacting mechanism of different photoresists in preparing periodic nanostructures with the LDW technique was discussed in detail.

  14. Optical Communication with Semiconductor Laser Diode. Interim Progress Report. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic; Sun, Xiaoli

    1989-01-01

    Theoretical and experimental performance limits of a free-space direct detection optical communication system were studied using a semiconductor laser diode as the optical transmitter and a silicon avalanche photodiode (APD) as the receiver photodetector. Optical systems using these components are under consideration as replacements for microwave satellite communication links. Optical pulse position modulation (PPM) was chosen as the signal format. An experimental system was constructed that used an aluminum gallium arsenide semiconductor laser diode as the transmitter and a silicon avalanche photodiode photodetector. The system used Q=4 PPM signaling at a source data rate of 25 megabits per second. The PPM signal format requires regeneration of PPM slot clock and word clock waveforms in the receiver. A nearly exact computational procedure was developed to compute receiver bit error rate without using the Gaussion approximation. A transition detector slot clock recovery system using a phase lock loop was developed and implemented. A novel word clock recovery system was also developed. It was found that the results of the nearly exact computational procedure agreed well with actual measurements of receiver performance. The receiver sensitivity achieved was the closest to the quantum limit yet reported for an optical communication system of this type.

  15. Controlled far-field pattern selection in diffraction-coupled semiconductor laser arrays

    SciTech Connect

    Wilcox, J.Z.; Jansen, M.; Silver, A.H.; Yang, J.J.J.; Simmons, W.W.

    1988-08-16

    A diffraction-coupled semiconductor laser array is described capable of being switched between essentially in-phase and essentially out-of-phase supermodes of operation. The array consists of: a waveguide section having an array of semiconductor lasers coupled together by evanescent coupling, and having one at least partially reflective optical emission element; a diffraction section connected to the waveguide section, and having an at least partially reflective optical emission element that cooperates with the optical emission element in the waveguide section, to produce lasing of the array; wherein the dimensions of the waveguide section and the diffraction section are selected to encourage in-phase lasing of the array; and wherein the diffraction section and the waveguide section have electrically isolated contact layers to switch the array, by independent current injection, between two different operating states, one of which promotes lasing in the in-phase supermode and the other of which promotes lasing in the out-of-phase supermode.

  16. Transversely diode-pumped Q-switched Nd : YAG laser with injection of radiation from a single-frequency semiconductor laser

    NASA Astrophysics Data System (ADS)

    Bogdanovich, M. V.; Duraev, V. P.; Kalinov, V. S.; Kostik, O. E.; Lantsov, K. I.; Lepchenkov, K. V.; Mashko, V. V.; Ryabtsev, A. G.; Ryabtsev, G. I.; Teplyashin, L. L.

    2016-10-01

    A Q-switched Nd : YAG laser with a high-power transverse diode pumping and injection of seed radiation generated by a single-frequency semiconductor laser is described. The threshold seed radiation power at which the Q-switched Nd : YAG switches to the single-frequency mode is 0.44 {\\text{mW}} (radiation intensity 5.6 × 10-2 {\\text{W}} {\\text{cm}}-2). With increasing injection power, the spectral and power characteristics of the Q-switched laser almost do not change at a constant excitation of its active medium. The spectral linewidth of the Q-switched Nd : YAG laser with injection from a TLD-1060-14BF single-frequency semiconductor laser module does not exceed 90 {\\text{MHz}} (wavelength 1064 {\\text{nm}}).

  17. Dual-pumped nondegenerate four-wave mixing in semiconductor laser with a built-in external cavity

    NASA Astrophysics Data System (ADS)

    Wu, Jian-Wei; Qiu, Qi; Hyub Won, Yong

    2017-04-01

    In this paper, a semiconductor laser system consisting of a conventional multimode Fabry–Pérot laser diode with a built-in external cavity is presented and demonstrated. More than two resonance modes, whose peak levels are significantly higher than other residual modes, are simultaneously supported and output by adjusting the bias current and operating temperature of the active region. Based on this device, dual-pumped nondegenerate four-wave mixing—in which two pump waves and a single signal wave are simultaneously fed into the laser, and the injection power and wavelength of the injected pump and signal waves are changed—is observed and discussed thoroughly. The results show that while the wavelengths of pump wave A and signal wave S are kept constant, the other pump wave B jumps from about 1535 nm to 1578 nm, generating conversion signals with changed wavelengths. The achieved conversion bandwidth between the primary signal and the converted signal waves is broadly tunable in the range of several terahertz frequencies. Both the conversion efficiency and optical signal-to-noise ratio of the newly generated conversion signals are adopted to evaluate the performance of the proposed four-wave mixing process, and are strongly dependent on the wavelength and power of the injected waves. Here, the attained maximum conversion efficiency and optical signal-to-noise ratio are close to ‑22 dB and 15 dB, respectively.

  18. Efficient power extraction in surface-emitting semiconductor lasers using graded photonic heterostructures.

    PubMed

    Xu, Gangyi; Colombelli, Raffaele; Khanna, Suraj P; Belarouci, Ali; Letartre, Xavier; Li, Lianhe; Linfield, Edmund H; Davies, A Giles; Beere, Harvey E; Ritchie, David A

    2012-07-17

    Symmetric and antisymmetric band-edge modes exist in distributed feedback surface-emitting semiconductor lasers, with the dominant difference being the radiation loss. Devices generally operate on the low-loss antisymmetric modes, although the power extraction efficiency is low. Here we develop graded photonic heterostructures, which localize the symmetric mode in the device centre and confine the antisymmetric modes close to the laser facet. This modal spatial separation is combined with absorbing boundaries to increase the antisymmetric mode loss, and force device operation on the symmetric mode, with elevated radiation efficiency. Application of this concept to terahertz quantum cascade lasers leads to record-high peak-power surface emission (>100 mW) and differential efficiencies (230 mW A(-1)), together with low-divergence, single-lobed emission patterns, and is also applicable to continuous-wave operation. Such flexible tuning of the radiation loss using graded photonic heterostructures, with only a minimal influence on threshold current, is highly desirable for optimizing second-order distributed feedback lasers.

  19. Nanoscale Photoconductivity Imaging of Thin-film Semiconductors by Laser-assisted Microwave Impedance Microscopy

    NASA Astrophysics Data System (ADS)

    Chu, Zhaodong; Wu, Di; Ren, Yuan; Yang, Seungcheol; Sun, Liuyang; Li, Xiaoqin; Lai, Keji

    The photo-response of semiconductors is usually studied by detecting the photocurrent across source-drain electrodes under light illumination. By integrating the microwave impedance microscopy (MIM) technique with focused-laser stimulation, we are able to perform the real-space photoconductivity mapping of photo-sensitive materials without the need of patterning contact electrodes. Here, we report the MIM results of various thin-film materials, such as In2Se3 nano-sheets and transition metal dichalcogenides (TMD) flakes, illuminated by laser beams of different wavelengths in the ambient condition. With no or below-gap illumination, the samples were highly resistive, as indicated by the low MIM signals. The MIM contrast emerges under above-gap light and increases as increasing laser intensity, which clearly demonstrates the local imaging of photoconductivity rather than the transport photocurrent. Interestingly, clear domain structures with mesoscopic length scales were seen in the data due to the coexistence of multiple phases in In2Se3. The unique combination of MIM and laser stimulation thus provides a new direction to explore the microscopic origin of various light-driven phenomena in complex systems. We gratefully acknowledge financial support from NSF.

  20. Quantum cascade semiconductor infrared and far-infrared lasers: from trace gas sensing to non-linear optics.

    PubMed

    Duxbury, Geoffrey; Langford, Nigel; McCulloch, Michael T; Wright, Stephen

    2005-11-01

    The Quantum cascade (QC) laser is an entirely new type of semiconductor device in which the laser wavelength depends on the band-gap engineering. It can be made to operate over a much larger range than lead salt lasers, covering significant parts of both the infrared and submillimetre regions, and with higher output power. In this tutorial review we survey some of the applications of these new lasers, which range from trace gas detection for atmospheric or medical purposes to sub-Doppler and time dependent non-linear spectroscopy.